This is what a render looks like using Vegas 21 and Vukoder (the newest but older also didn't work).
I render in 954x720 resolution (1430x1080 also didn't work)
Rencoding with Mainconcept goes smoothly.
Screenshot is cropped.
It seems the resolution is the problem -- if it's not divisible by 4, that's how it works out.
But if I render losslessly and then manually render with ffmpeg, the resolution of 934x720 comes out correctly.
I tried rendering today in 694x564 and 1050x1080 resolutions. In both cases the effect is as above, i.e. shifted chroma (?). Is there any chance to improve this?