@donq Hi, it's still there on the ftp servers, but as @leocg wrote there's already a newer major version available - 79.0.4100.0.
Do you still experiencing this problem in the latest version?
Have you already reported it using Opera's bugs & suggestions report form?
Thank you for asking
Problem remained, but it was actually not Opera problem.
Teams interface in Opera is changed and while switcing tabs off the Teams chat tab, Opera displayed some kind of popup, which conflicted with my home-made tab switcher extension (which just switched focus back to Teams tab).
After disabling my extension I did see Teams popup, after closing it (and making sure that no kind of popups and popouts are enabled - I hate them anyway) I could re-enable my extension again.
Thereby everything is working again and no need for bug report