Glitching renders in v20. Same render in v19 compared

Render in v19; https://k00.fr/3b8e4f6l
Render in v20; https://k00.fr/dp1f1k4r

Please fix this asap. This is unacceptable and should have been fixed in beta stage. You cannot introduce rendering artifacts in clips without any timing effects..

Quick fix/workaround is to set timeline settings to HD. it renders without artifacts then. but I want it in 4k, in the end. so still: please fix it.

And also in some video platforms like in Castr the Resolve 20 rendered video and audio is out of sync.
Resolve 19 audio video sync is ok.