Comment 12 for bug 1816497

The landing page for the build has disappeared: https://code.launchpad.net/~osomon/+snap/chromium-snap-from-source-enable-vaapi so it's possible that your installation has reverted to the main branch again.

For what it's worth, there is another working option available that we can try: https://launchpad.net/~saiarcot895/+archive/ubuntu/chromium-beta

I'd honestly prefer to use an official Ubuntu build but the one above has served me consistently well on previous system so I'll probably stick with that until we see a main branch build with vaapi support.