How can deblend this ?

[Selur]

Would need an 'as untouched as possible' sample of the source to say for sure to really see what is happening.
Chroma artifacts can occur due to improper deinterlacing / ivtc /...
Depending on the nature of the artifacts, filtering might be best applied to the separate fields of the source.
Sometimes only, machine learning stuff (or really arcane scripting) can help.
Without a sample, for chroma issues I would recommend:
a. try the derainbow filters with different settings
b. try denoise filters with high thresholds on chroma only
c. depending on the anime / cartoon someone might have already posted a model over at https://openmodeldb.info/ that was trained for that or similar content that might help.
d. depending on the nature of the artifacts there might be a chroma shift or chroma bleeding,...

=> share one or multiple short samples ('as untouched as possible') with me and I might be able to suggest something.

Cu Selur

Ps.: sometimes stuff is just too broken to get 'properly' fixed,...