This may seem trivial, but the name "Mastodon" never quite works for me. Compared to "Twitter" it is less descriptive and has an extra syllable. That might not seem important, but to achieve scale it might be off-putting to prospective users.

Also, anyone familiar with the term "mastodon" knows it refers to an extinct mamal, aka "a dinosaur". Possibly a not great look.

Whether a new name would even be possible at this point is not something that I have an informed opinion on.

Disclosure: I dont use Mastodon or Twitter, or basically any social media.