It looks like point sampled (nearest neighbor) chroma . It's just duplicating samples up to 4:4:4 then RGB, then back down to 4:2:2 when exporting a 4:2:2 format
So if you export some 4:2:2 format, you can downsample back to 4:2:0 using chromaresample="point" and it will look close to what you started with
#exported 4:2:2 format like prores
ConvertBits(8)
ConvertToYV12(chromaresample="point")
Or you can use avsresize eg. for 10bit , but 4:2:0
z_ConvertFormat(pixel_type="YUV420P10", resample_filter="point")
(I tested this on some patterns in Resolve Studio 15, similar conditions 720x480 x264 4:2:0 import, 720x480 timeline settings, 422 export)