In fact, for 3k people you just can use Youtube Live

Maybe Brave Talk? but it’s not free for big groups. Although it’s cheap: 7 USD/Month. And it doesn’t require an account.

I forgot to mention, I have Element Classic on my mobile, not sure about the X one

I’ve just checked, and I saw it has the little camera button for videocalls at the top right of the screen. Unless you’re talking about phone calls

As far as I know, Matrix is free, and you can use it through many apps who handle this communication protocol. The most well known is Element

ooh, so it was you then!! 😠