Restoring badly digitized VHS

[Selur]

To me, 4-weave doesn't really seem stable, but I agree the text is not broken.
That said, I too would have expected for your code to work, but I suspect somewhere ffmpeg does some interpolation, so upscaling before Stab and downscaling afterwards:

# Imports
import vapoursynth as vs
# getting Vapoursynth core
import ctypes
import sys
import os
core = vs.core
# Limit frame cache to 48473MB
core.max_cache_size = 48473
# 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/libmotionmask.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/ColorFilter/Retinex/Retinex.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/vszip.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/CTMF/CTMF.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/TCanny.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/libfillborders.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/libtemporalmedian.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/Cnr2/libcnr2.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/SharpenFilter/MSmooth/libmsmoosh.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/FrameFilter/ReduceFlicker/ReduceFlicker.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/GrainFilter/AddGrain/AddGrain.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/NEO_FFT3DFilter/neo-fft3d.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/DFTTest/DFTTest.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/EEDI3m_opencl.dll")# vsQTGMC
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/ResizeFilter/nnedi3/NNEDI3CL.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/fmtconv.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DeinterlaceFilter/Bwdif/Bwdif.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/akarin.dll")
core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/SourceFilter/DGDecNV/DGDecodeNV_AVX2.dll")
# defining beforeDeCross-function - START
def beforeDeCross(clip):
  core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/MiscFilter/MiscFilters/MiscFilters.dll")
  core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/DenoiseFilter/ZSmooth/zsmooth.dll")
  core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/libmvtools.dll")
  core.std.LoadPlugin(path="F:/Hybrid/64bit/vsfilters/Support/DePan.dll")
  import stabilize
  clip = core.std.SeparateFields(clip, tff=True)
  height = clip.height
  clip = core.resize.Bicubic(clip, height=height*2)
  clip = stabilize.Stab(clp=clip, dxmax=0, dymax=1, range=1)
  clip = core.resize.Bicubic(clip, height=height)
  clip = core.std.DoubleWeave(clip, tff=True)
  clip = core.std.SelectEvery(clip, 2, 0)
  clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff
  return [clip]
# defining beforeDeCross-function - END

# Import scripts
import vs_temporalfix
import fromDoom9
import SpotLess
import qtgmc
import validate
# Source: 'C:\Users\Selur\Desktop\1-source.mkv'
# Current color space: YUV420P8, bit depth: 8, resolution: 704x480, frame rate: 29.97fps, scanorder: top field first, yuv luminance scale: limited, matrix: 470bg, transfer: bt.601, primaries: bt.601 ntsc, format: mpeg-2
# Loading C:\Users\Selur\Desktop\1-source.mkv using DGSource
clip = core.dgdecodenv.DGSource("J:/tmp/mkv_43360fd7b44504b5cea6a7b5fab0c634_853323747.dgi",fieldop=0)# 29.97 fps, scanorder: top field first
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 29.97fps
clip = core.std.AssumeFPS(clip=clip, fpsnum=30000, fpsden=1001)
# making sure the detected scan type is set (detected: top field first)
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff
[clip] = beforeDeCross(clip)
# clip current meta; color space: YUV420P8, bit depth: 8, resolution: 704x480, fps: 29.97, color matrix: 470bg, yuv luminance scale: limited, scanorder: top field first, full height: true
# Deinterlacing using QTGMC
clip = qtgmc.QTGMC(Input=clip, Preset="Fast", TFF=True, opencl=True) # new fps: 59.94
# Making sure content is preceived as frame based
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_PROGRESSIVE) # progressive
# Spot removal using SpotLess
clip = SpotLess.SpotLess(clip=clip, radT=3, rec=True, pel=1, smoother="zsmooth")
# removing flickering using ReduceFlicker
clip = core.rdfl.ReduceFlicker(clip=clip, strength=3, aggressive=1)
# removing flickering using Small Deflicker
clip = fromDoom9.Small_Deflicker(clip=clip, preset=3, cnr=True, zsmooth=True)
# changing range from limited to full range for vsTemporalfix
clip = core.resize.Bicubic(clip, format=vs.YUV420P8, range_in_s="limited", range_s="full")
# setting color range to PC (full) range.
clip = core.std.SetFrameProps(clip=clip, _ColorRange=vs.RANGE_FULL)
# stabilizing using Temporalfix
clip = vs_temporalfix.vs_temporalfix(clip=clip)
# changing range from full to limited range for vsTemporalfix
clip = core.resize.Bicubic(clip, format=vs.YUV420P8,range_in_s="full", range_s="limited")
# setting color range to TV (limited) range.
clip = core.std.SetFrameProps(clip=clip, _ColorRange=vs.RANGE_LIMITED)
# adjusting output color from: YUV420P8 to YUV420P10 for NVEncModel
clip = core.resize.Bicubic(clip=clip, format=vs.YUV420P10)
# set output frame rate to 59.94fps (progressive)
clip = core.std.AssumeFPS(clip=clip, fpsnum=60000, fpsden=1001)
# output
clip.set_output()

does seem to work. (I also added deflickering&co for stabilization and SpotLess for cleanUp.)
=> https://www.mediafire.com/file/qo0zawd6h...2.mkv/file

The custom code I used:

core.std.LoadPlugin(path="%FILTERPATH%/MiscFilter/MiscFilters/MiscFilters.dll")
core.std.LoadPlugin(path="%FILTERPATH%/DenoiseFilter/ZSmooth/zsmooth.dll")
core.std.LoadPlugin(path="%FILTERPATH%/Support/libmvtools.dll")
core.std.LoadPlugin(path="%FILTERPATH%/Support/DePan.dll")
import stabilize
clip = core.std.SeparateFields(clip, tff=True)
height = clip.height
clip = core.resize.Bicubic(clip, height=height*2)
clip = stabilize.Stab(clp=clip, dxmax=0, dymax=1, range=1)
clip = core.resize.Bicubic(clip, height=height)
clip = core.std.DoubleWeave(clip, tff=True)
clip = core.std.SelectEvery(clip, 2, 0)
clip = core.std.SetFrameProps(clip=clip, _FieldBased=vs.FIELD_TOP) # tff

Cu Selur