Additional meeting and call-related features and issues within Microsoft Teams for business
I have just done a quick test, and it looks like the issue may have been resolved. I did not change versions as I was already on the latest version and no further updates have been released.
When I first joined a meeting today it flickered a little and then stopped, now when I join subsequent meetings even with the app closed there is no flickering. I guess this may have been something they fixed server side, which is why no update to the app was needed.
I have not yet tested it on other Macs, but it's now working on mine. I did update to 13.6, so that cloud have also resolved the issue I guess.