Me and @wayward have been playing Spelunky 2 together on Switch and it had been working perfectly. I know multiplayer was iffy on some other platforms (or at least PC) but on Switch it was like playing locally. It just worked.
Well, a few weeks ago they did a big overhaul for multiplayer to fix it on some platforms and improve crossplay and the result was that between every level the game would freeze for 5 seconds with a "syncing" alert and no indication it was doing anything.
A few days ago the game got patched with some further fixes to multiplayer and on the Switch it appears to be unplayable:
We switched to PC and it's better than it used to be (certainly playable) but nowhere near as good as it was on switch