swscale yuv2rgb crops image or causes glitches

[iss]

Summary of the bug:
From debugging the issue this seems to happen only when video resolution is not divisible by 32.

How to reproduce:

ffmpeg.exe -ss 00:00:00.50 -i test.avi -vframes 1 -pix_fmt rgba test.png

ffmpeg version N-103795-g140eac77a9-g6e26015a6b+1 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10.3.0 (Rev5, Built by MSYS2 project)

This may be same report as #8871, but in this case8 px on left side are corrupted.
This issue happens in Blender, but there every line of output is corrupted like this.

[iss]

Test file

[iss]

Broken output

[Balling]

May be related to latest breaking of everything due to multithreading in swscale. https://ffmpeg.org/pipermail/ffmpeg-devel/2021-September/284897.html
May be will be fixed with:
Can you reproduce with zscale?

[iss]

Replying to Balling:

May be related to latest breaking of everything due to multithreading in swscale. https://ffmpeg.org/pipermail/ffmpeg-devel/2021-September/284897.html
May be will be fixed with:

I am sure I was able to reproduce this issue with build few months old, from around may/june 2021. Unfortunately I didn't note exact commit.

Can you reproduce with zscale?

This happens during pixel format conversion, no image resizing is done, not sure if zscale is applicable. From docs I don't quite see how at least.

[pdr0]

zscale is ok

ffmpeg -ss 00:00:00.50 -i test.avi -vf zscale=matrixin=170m,format=gbrap -vframes 1 testz.png

swscale was ok if you check about month ago. Not sure which commit broke it, but current version has the issue

[Balling]

Does not happen anymore, moreover png is bitperfect with old ffmpeg when

swscale was ok if you check about month ago