hm, right, i forgot about startupCache, i cleaned it on my phone while debugging login and other stuff but on normal rpm update it's apparently not touched.
Can you remove .cache/rockpool/.mozilla/startupCache/startupCache.4.little and try to re-launch app again to confirm login feature? I'll then think of some hook to invalidate the cache when jsm is updated.

As for calendar, I got already another report, planning to dig it tomorrow once I have events in timeline window (my cal is very sparse).