random frame render issues in AE 26.2.1

I’m working in 32-bit float for a broadcast UHD job, and when I try to render final output as a ProRes QuickTime, random frames (around 1 in 50) render with colour/luma shifts. It’s completely random -  I had to clear memory/cache until it rendered successfully.  And for longer clips, I was able to get it to render by manually placing single-frame adjustment layers with a levels effect (not set) over the frames that had the glitches.
This is a serious bug. I tried render with multiprocessing disabled, but it still happens. I can supply projects and examples showing the issues to AE engineers if needed. Anyone else having this issue?