Encrypted DMs and other DM upgrades rolling out this week

Unrelated, but genuine question from someone who doesn't really use twitter. What happened to Twitter's QoS falling apart after Musk laid off all those people? Were the warnings overblown and unrealistic, or is there just an inside story? I feel like I heard a lot about how they were doomed and now it seems like they're rolling out new features.

Are there details about how key management works? Where are the keys stored, what has access to them, etc? Because this tweet is empty hype.

E2e encryption or just not stored in plaintext on their servers?

Musk's extreme lack of credibility aside, why would anyone use Twitter for this when there are already many very popular alternatives that have been around for years?