It’s still usable if you’re not on English side of Twitter.
For example, recent Indonesian political movement relied on Twitter for discussion and updates. Mastodon or any fediverse is simply too niche and most people don’t have money to fund local general instance. There were several local fedi instance (Mastodon and Lemmy), but all of them quickly dead for low donation.
Japanese-side is still alive (in positive manner) but people are making backup account on Bluesky and Japanese Misskey instances.