How is called this kind of "defect" and how to mitigate? (if possible)

[Selur]

Okay, no wonder that isn't working!
Your script is:

# Imports
import vapoursynth as vs
# getting Vapoursynth core
import sys
import os
core = vs.core
# Import scripts folder
scriptPath = 'C:/Program Files/Hybrid/64bit/vsscripts'
sys.path.insert(0, os.path.abspath(scriptPath))
# loading plugins
core.std.LoadPlugin(path="C:/Program Files/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/LSMASHSource.dll")
# defining beforeEnd-function - START
def beforeEnd(clip):
  # converting interlaced to half-height progressive for filtering (vsMCTemporalDenoise) (separate fields)
  clip = core.resize.Bicubic(clip=clip, format=vs.YUV444P8, range_s="limited")
  clip = core.std.SeparateFields(clip, tff=False)
  clipEven = clip[::2] # resolution 720x288
  clipEven = core.std.SetFrameProps(clip=clipEven, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
  clipOdd = clip[1::2] # resolution 720x288
  clipOdd = core.std.SetFrameProps(clip=clipOdd, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
  # denoising using MCTemporalDenoise
  clipEven = denoise.MCTemporalDenoise(i=clipEven, settings="very high", ncpu=10)
  # denoising using MCTemporalDenoise
  clipOdd = denoise.MCTemporalDenoise(i=clipOdd, settings="very high", ncpu=10)
  # converting half-height progressive to interlacedbefore deinterlacing
  clip = core.std.Interleave([clipOdd, clipEven])
  clip = core.std.DoubleWeave(clip=clip, tff=False)  # resolution 720x576
  clip = core.std.SelectEvery(clip, 2, 0)
  clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff
  # Deinterlacing using TIVTC
  clip = core.tivtc.TFM(clip=clip, chroma=True)
  clip = core.tivtc.TDecimate(clip=clip, mode=7, rate=23.9760, dupThresh=0.04, vidThresh=3.50, sceneThresh=15.00)# new fps: 23.976
  # Making sure content is preceived as frame based
  clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
  # applying anti aliasing using santiag
  clip = antiAliasing.santiag(c=clip, strh=3, strv=3, nns=2, qual=2, pscrn=2, opencl=True)
  return clip
# defining beforeEnd-function - END

# Import scripts
import validate
# Source: 'C:\Users\Bfield\Desktop\defect.avi'
# Current color space: YUV420P8, bit depth: 8, resolution: 720x576, frame rate: 30fps, scanorder: progressive, yuv luminance scale: limited, matrix: 470bg, format: ULH0
# Loading C:\Users\Bfield\Desktop\defect.avi using LWLibavSource
clip = core.lsmas.LWLibavSource(source="C:/Users/Bfield/Desktop/defect.avi", format="YUV420P8", stream_index=0, cache=0, prefer_hw=0)
frame = clip.get_frame(0)
# setting color matrix to 470bg.
clip = core.std.SetFrameProps(clip, _Matrix=vs.MATRIX_BT470_BG)
# setting color transfer (vs.TRANSFER_BT601), if it is not set.
if validate.transferIsInvalid(clip):
  clip = core.std.SetFrameProps(clip=clip, _Transfer=vs.TRANSFER_BT601)
# setting color primaries info (to vs.PRIMARIES_BT470_BG), if it is not set.
if validate.primariesIsInvalid(clip):
  clip = core.std.SetFrameProps(clip=clip, _Primaries=vs.PRIMARIES_BT470_BG)
# setting color range to TV (limited) range.
clip = core.std.SetFrameProps(clip=clip, _ColorRange=vs.RANGE_LIMITED)
# making sure frame rate is set to 30fps
clip = core.std.AssumeFPS(clip=clip, fpsnum=30, fpsden=1)
# making sure the detected scan type is set (detected: progressive)
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
clip = beforeEnd(clip)
# set output frame rate to 30fps (progressive)
clip = core.std.AssumeFPS(clip=clip, fpsnum=30, fpsden=1)
# output
clip.set_output()

In your custom section you use:
'denoise','tivtc','antiAliasing' but you don't import the used scripts, or load the required plugins.

No clue why you are using a custom section, to begin with.
The stuff I did in post #3, you can archive by:

• loading your source
  
• enabling and settings 'Filtering->(De-)Interlace/Telecine->Overwrite input scan type to' to 'telecine'
  
• setting 'Filtering->(De-)Interlace/Telecine->TIVTC Settings->TDecimate->Mode' to '7'
  
• setting 'Filtering->(De-)Interlace/Telecine->TIVTC Settings->TDecimate->Rate' to '23.976'
  
• setting 'Filtering->Vapoursynth->Misc->Script->Filter interlace handling' to 'separate fields'
  
• enabling 'Filtering->Vapoursynth->DeNoise->MC Temporal Denoise'
  
• setting 'Filtering->Vapoursynth->DeNoise->MC Temporal Denoise->Settings' to 'very high' (optionall increasing ncpu to 10)
  
• switching to 'Filtering->Vapoursynth->Misc->Filter Order/Queue' and moving 'MCTemporalDenois' above 'Deinterlace'
  
• enabling 'Filtering->Vapoursynth->Line->AntiAliasing->Santiag'
  
• setting 'Filtering->Vapoursynth->Line->AntiAliasing->Santiag->strength->h&v' both to '3 (optionally enabling 'OpenCL')
  

For me, the Vapoursynth Script Preview then shows:

# Imports
import vapoursynth as vs
# getting Vapoursynth core
import ctypes
import sys
import os
core = vs.core
# Import scripts folder
scriptPath = 'F:/Hybrid/64bit/vsscripts'
sys.path.insert(0, os.path.abspath(scriptPath))
# Loading Support Files
Dllref = ctypes.windll.LoadLibrary("F:/Hybrid/64bit/vsfilters/Support/libfftw3f-3.dll")
# loading plugins
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/libsangnom.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/fmtconv.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/EEDI2.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/EEDI3m_opencl.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/ResizeFilter/nnedi3/NNEDI3CL.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DeinterlaceFilter/TIVTC/libtivtc.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/MiscFilter/MiscFilters/MiscFilters.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/TTempSmooth/TTempSmooth.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/DFTTest/DFTTest.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/NEO_FFT3DFilter/neo-fft3d.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/DCTFilter.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DeblockFilter/Deblock/Deblock.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/libmvtools.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/LSMASHSource.dll")
# Import scripts
import antiAliasing
import denoise
import validate
# Source: 'C:\Users\Selur\Desktop\defect.avi'
# Current color space: YUV420P8, bit depth: 8, resolution: 720x576, frame rate: 30fps, scanorder: telecine, yuv luminance scale: limited, matrix: 470bg, format: ULH0
# Loading C:\Users\Selur\Desktop\defect.avi using LWLibavSource
clip = core.lsmas.LWLibavSource(source="C:/Users/Selur/Desktop/defect.avi", format="YUV420P8", stream_index=0, cache=0, prefer_hw=0)
frame = clip.get_frame(0)
# setting color matrix to 470bg.
clip = core.std.SetFrameProps(clip, _Matrix=vs.MATRIX_BT470_BG)
# setting color transfer (vs.TRANSFER_BT601), if it is not set.
if validate.transferIsInvalid(clip):
  clip = core.std.SetFrameProps(clip=clip, _Transfer=vs.TRANSFER_BT601)
# setting color primaries info (to vs.PRIMARIES_BT470_BG), if it is not set.
if validate.primariesIsInvalid(clip):
  clip = core.std.SetFrameProps(clip=clip, _Primaries=vs.PRIMARIES_BT470_BG)
# setting color range to TV (limited) range.
clip = core.std.SetFrameProps(clip=clip, _ColorRange=vs.RANGE_LIMITED)
# making sure frame rate is set to 30fps
clip = core.std.AssumeFPS(clip=clip, fpsnum=30, fpsden=1)
# making sure the detected scan type is set (detected: telecine)
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff
# converting interlaced to half-height progressive for filtering (vsMCTemporalDenoise) (separate fields)
clip = core.resize.Bicubic(clip=clip, format=vs.YUV444P8, range_s="limited")
clip = core.std.SeparateFields(clip, tff=False)
clipEven = clip[::2] # resolution 720x288
clipEven = core.std.SetFrameProps(clip=clipEven, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
clipOdd = clip[1::2] # resolution 720x288
clipOdd = core.std.SetFrameProps(clip=clipOdd, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
# denoising using MCTemporalDenoise
clipEven = denoise.MCTemporalDenoise(i=clipEven, settings="very high", ncpu=10)
# denoising using MCTemporalDenoise
clipOdd = denoise.MCTemporalDenoise(i=clipOdd, settings="very high", ncpu=10)
# converting half-height progressive to interlacedbefore deinterlacing
clip = core.std.Interleave([clipOdd, clipEven])
clip = core.std.DoubleWeave(clip=clip, tff=False)  # resolution 720x576
clip = core.std.SelectEvery(clip, 2, 0)
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff
# Deinterlacing using TIVTC
clip = core.tivtc.TFM(clip=clip)
clip = core.tivtc.TDecimate(clip=clip, mode=7, rate=23.9760, dupThresh=0.04, vidThresh=3.50, sceneThresh=15.00)# new fps: 23.976
# Making sure content is preceived as frame based
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
# applying anti aliasing using santiag
clip = antiAliasing.santiag(c=clip, strh=3, strv=3, nns=2, qual=2, pscrn=2, opencl=True)
# adjusting output color from: YUV444P8 to YUV420P10 for NVEncModel
clip = core.resize.Bicubic(clip=clip, format=vs.YUV420P10, range_s="limited")
# set output frame rate to 23.976fps (progressive)
clip = core.std.AssumeFPS(clip=clip, fpsnum=24000, fpsden=1001)
# output
clip.set_output()

In theory, you could use a custom section, but when using a custom section you are responsible to load all dependencies&co.

Cu Selur