The recent 4.2.0 release has introduced an opt-in search feature, so that's changing. About half of Mastodon instances are on 4.2 now (according to FediDB), an

The recent 4.2.0 release has introduced an opt-in search feature, so that's changing. About half of Mastodon instances are on 4.2 now (according to FediDB), and it looks like future releases will prompt existing users to check whether they want to opt-in.