I'm seeing a lot of conversation around usernames and the implementation of reserved words or profanity/harmful language filters. This ties in to to a soon-to-be-available feature in Mastodon that will enable rules to proactively moderate account usernames. The IFTAS Community Library has a reserved words resource page at

Reserved Words Resources – IFTAS

As with all moderation tools, all friction is good friction, nothing is perfect. Used well, reserved word rules are a vital tool in the toolkit.