My first thought was also to mute the chat, is this possible?

Honestly group chats are a common source of annoyance for many people, what you’re experiencing is certainly not unusual so don’t beat yourself up for muting the chat. You aren’t paid outside of work hours I’m guessing? So it’s not reasonable for you to be expected read this stuff in out of work hours imo.

You can still be perfectly pleasant when you’re on paid time.