I get occasional spam - I'd guess it's because you've never joined a public group or shared your handle anywhere?

I indeed never have joined a public group and never shared my handle with non-people I know.

It's especially bad when you have a public username that is also kinda popular. They made "hide chat and mute for unknown contacts" free at least...

If you join public groups with a lot of users you end up on a bunch of spam lists and get smashed by bots.