Somebody documented Mastodon's new search implementation, now that the dust has settled.
SearchSearch in Mastodon, and the wider Fediverse, can be a confusing and contentious topic.
Here's the search documentation from the streams repository:
https://unfediverse.com/help/develop/en/Federated_SearchSummary:
I'll let others decide which one actually federates and is compatible with the rest of the fediverse; and which one actually doesn't and isn't.
Although the search modifiers are an interesting touch. These could be added to the streams repository in about an hour. Give or take.