No point in reporting this bug upstream, they will not be able to reproduce it as it's related to the hardware video acceleration patch that Debian has recently started applying on top of the upstream Chromium: https://salsa.debian.org/chromium-team/chromium/blob/c88b97a6dc183a6a7f8a05aee9e99957285a9371/debian/patches/fixes/vaapi.patch
As I can see, there are two possibilities here: 1. the patch got broken in Chromium 79, in which case it needs to be updated and fixed 2. the issue is not with Chromium but the VAAPI library or the hardware you use, in which case you could make Chromium use different GPU (integrated graphics) or disable hardware video acceleration altogether, either by passing some flag to Chromium (removing --ignore-gpu-blacklist from /etc/chromium.d/default-flags might work too) or rebuilding Chromium without the patch
