Thanks, streepje8! Take your time, it's not urgent. I thought it might be an issue for others too, so you should check. Some details that might be helpful: I've done no more than joining and reading the channels for the first tries and no more than introduced myself on one of the following tries, when I was not kicked and got time for sending the message.
Thought kicks were due to inactivity, but it was hard to send a message between time after 10 minutes of initial waiting and kick, so that looked strange 🙃