What about a derainbow filter like SSIQ on hybrid or other chroma denoise? On TVAI there are all the useful filter but miss this, for some old dvd… 
If you can drop down to the TVAI command line, you can insert the dedot filter into the filter chain to reduce rainbowing. It is not exposed in the GUI, but it is in TVAI’s underlying FFmpeg build. You can use FFplay to preview the effect of the filter.
$ ffmpeg -hide_banner -h filter=dedot
Filter dedot
Reduce cross-luminance and cross-color.
slice threading supported
Inputs:
#0: default (video)
Outputs:
#0: default (video)
dedot AVOptions:
m <flags> ..FV....... set filtering mode (default dotcrawl+rainbows)
dotcrawl ..FV.......
rainbows ..FV.......
lt <float> ..FV....... set spatial luma threshold (from 0 to 1) (default 0.079)
tl <float> ..FV....... set tolerance for temporal luma (from 0 to 1) (default 0.079)
tc <float> ..FV....... set tolerance for chroma temporal variation (from 0 to 1) (default 0.058)
ct <float> ..FV....... set temporal chroma threshold (from 0 to 1) (default 0.019)
This filter has support for timeline through the 'enable' option.
