I usually don’t write about the Microsoft Windows ecosystem, but this one took a while to figure out and I hope it saves other people time. The setup: Microsoft Windows, the Teams application, a Canon EOS camera attached over a no-name HDMI-to-USB video grabber being used as a web cam. The issue: video sporadically freezes in the Microsoft Teams app only during a call once other participants have joined. The video will not freeze in preview, nor do any other Windows applications cause problems. Video will also work fine in the Microsoft Teams web version. Also note that the setup works fine with Ubuntu.
It turns out that the HDMI-to-USB video grabber was (rarely) dropping frames. The missing frames don’t lead to visible artefacts like stutter or freezes with any other applications except Teams. After trying various random hacks and not finding anything useful in the Teams logs, I replaced the video grabber with an Elgato Camlink 4K which ever since works flawlessly.
George's Techblog 