Randomly video surpressing and problems after screensharing

I’m a new user. I started last weekend to use the free online jitsi meet with only 5 people (placed in Southamerica and Europe) in 3 hours meetings.
1-Technical background:

  • Logitech camera with included mic.
  • I have also installed OBS, which creates a virtual OBS camera.
  • Connectivity over 500 Mbps in both directions (up and download)
  • Windows 10
  • Browser Firefox

Issues found:
1- Problem after sharing screen:
After having shared my screen (app Libreoffice Impress), when finishing sharing, the other paarticipants couldn’t see me anymore. Apparently it sent me to the OBS virtual camera, which I was not using.
The others were only able to see the capital letter of my user name, but not me.
I had to quit and join again, so the others could see me again.
2- The next day, we noticed that, although I avoided screensharing (because of the prior experience), randonly the videos of the participants were disabled with some message related to bandwith. This included myself too! Sometimes I could see some of the others, suddenly not, suddenly some of them appeared again and so on. None of us had an idea on how to solve this.
It’s a pity, because I found the system very good, with very valuable functionalities, but when working with it, these kind of issues prevents one to keep using it.
But before doing that: any hints or suggestions? Maybe we have done something wrong?
Please note that with other systems, in their free versions (zoom, Skype, Google Meet, etc.) I never experienced such kind of automatic bandwidth messages/restrictions.
Thanks in advance for your help!