Videos randomly disappearing in group conference

My wife started today using Jitsi for her group video ballet lessons, with up to 12 participants.
Is using Electron based client, installed on a KDE Neon PC.
All working fine so far, except for reasons I didn’t understand sometimes almost all video streams from the other users are disappearing.
They are able to see her, but she is not able to see them. After a few seconds (even 20-30) they randomly re-appear. This is a problem for a ballet teacher.
The remote server we are using it’s at all not saturated (barely used in fact). The 4G+ Internet connection we are using is working as normally even if sometimes good other times not optimal. The participants connection seems working normally.
Any suggestion how to troubleshoot this.

This MIght be a Bug report it here

Wondering if the Electron client might have a role?
The browser is performing the same as the client?
Or might be a standard behavior if the admin is low on bandwidth (discovered during some periods was very low)?
Didn’t have opportunity for many other tests, she is supposed to work using Jitsi every afternoon till late.

I’ll be able to test tomorow around 3PM GMT tomorrow pop me a message.