Maybe an issue on the back end skipping over all of the new private subs? I assume that many of the big subs had popular posts just before they went private, so the server has to spend more time skipping over private posts when rendering popular?
First and foremost, get third party clients working again. I am used to RiF. I tried the official app. It was very busy but showed much less useful information per screen. I could not even even leave it installed on my phone. It kept spamming (shitty) notifications to try to goose my engagement, even after I disabled them.
Anger about bad corporate decisions fades, but if I cannot comfortably use a site, I cannot come back.
It is not (just) for narcissism: it can fill a niche similar to RSS. When I was using Twitter, 90% of the posts I read were from companies or projects announcing news and updates. It also had a built in comments, so you have a single, shared discussion/q&a space in the same app.
Obviously, the biggest advantage it has over RSS (and Mastodon, so far) is critical mass. More creators have Twitter accounts than RSS feeds and for those that have both, the Twitter account is always more active.
I send photos and videos via MMS all the time and they work fine, but almost everyone I message is an Android user.