Oh: why did they just happen to cross "the threshold" while they were in there? What was going on? I assume it wasn't just convenient timing?
My guess is Kang had only planned and pruned his timeline up until the Lokis confront him and he makes his pitch, and he hadn't planned anything out beyond that. So it was just a matter of time after they got there that the timeline would start branching again.
Or maybe it has something to do with Loki and Syvlie creating strong nexus events, like they did on Lamentis. They never really explained why that happened. Kang decided on these two as his replacement for a reason... probably. Edit: or yeah maybe it has to do with Ravonna.
Anyway, I found the finale frustrating. Like sure season finales often have cliffhangers, but they generally also have some degree of resolution too. I guess confronting the true Timekeeper was resolution, but it was delivered in a way that didn't really feel like it to me? Because even that is just an introduction to something coming later.
It feels more like a mid-season finale, and I'm guessing by the end of Season 2, it'll feel more like one 12-episode season than two distinct 6-episode seasons. And ultimately that's fine, I just wish I had realized it was going to feel that way before going in so I could adjust my expectations accordingly.