Nextcloud talk => group conversation => shared screen suddenly freezes


I’m using NC20 with latest talk (10.1.2).
It appears that a shared screen (talk with 3 parties) sometimes randomly freezes at one party (sharing party and 3rd party still work fine).
This happened with regular Stun/Turn (local coturn) with and without hosted HPB (@Struktur AG).
Browser was Firefox(*) as well as Chrome.

only workaround we found so far is unsharing and re-sharing screen.

Any suggestions welcome!

Thanks - tullsta

(*) had to switch to CHrome since Firefox had consistently high CPU