There is also a massive ban wave is going on, some people are claiming to have lost followers overnight in three to four digits and losing following account as well - mostly content creators with years worth of organic posts. Extra salt to the wounds is the horde of spam bots don't seem too affected, if at all, because they don't show up on Firehose too often, which is probably how this newly implemented spam filtering picks up contents to decide on.
Some are speculating that some apps that had regular auto-tweets configured to be the culprit, which was later backed with some data, some are making up theories and rituals to protect accounts, some others are making backup accounts on Twitter itself, on Mastodon, or yet another platforms.
This seems like another round of Twitter's footgun towards tumblr, with some users making it out, and bulk of values and the community burning to the ground.
These events where Twitter does something like this trigger visible migration waves, observable from the FediVerse and elsewhere. There are several spikes in graphs over the past few months, that correlate with things like disabling TweetBot et al..
People are giving out advice to those who migrate away from Twitter to unfollow everyone that they were following, but leave the account undeleted to prevent impersonation in the future of a long-standing identity. The unfollowing is in order to not accrue stuff with a zombie account and in order to let the people still sticking with Twitter know that their followers are gone.
This fits with your observations: real followers gone, in a distinct wave, and robot accounts blithely continuing on.
But it means that it isn't banning at all. The people seeing this from the Twitter side and thinking that it's down to some mysterious "ban wave" aren't realizing that people are simply leaving them; voting with their feet. Account figures won't show it, but dropping follower figures and massively curtailed engagement with real people do.
The people who didn't like the politics have gone, or have been ejected. The people who were left exposed to unmoderated attacks have gone. The people who provided or who used the 3rd-party apps have gone. The people who relied upon a free-of-charge API to do all sorts of fun hobbyist and one-person-band things, from pictures of possums every hour to automated posts by artists and content creators, have stated that they're going, and have actually found themselves gone already in some cases within the past 30 hours, well before 2023-02-09.
Your boss messed up again, not knowing the community norms and thinking it won’t be a big deal, and it was, and his subordinates are running around rolling it back.
And you’re trying to set a new narrative for damage control. STFU and go away.
Some are speculating that some apps that had regular auto-tweets configured to be the culprit, which was later backed with some data, some are making up theories and rituals to protect accounts, some others are making backup accounts on Twitter itself, on Mastodon, or yet another platforms.
This seems like another round of Twitter's footgun towards tumblr, with some users making it out, and bulk of values and the community burning to the ground.