The key phrase in your statement is "on a friends invite server."

Okay, so if you don't already have a friend on Mastodon, then what? Have you actually looked at the list on https://joinmastodon.org/servers recently?

Half the comments here say it doesn't matter what server you choose, and half are saying to be sure to choose the one that aligns with your interests, which... see the list above for why that's an issue.

Panic? No. It's just an example of mastodon needlessly limiting itself in terms of usability right at the starting gate.