Seems like a local network issue on my side. For whatever reason, Microsoft pages (or at least part of them) seem to be inaccessible to me. Using a VPN the launcher starts up fine with my Microsoft identity as it should.
Issue can be closed as the problem lies elsewhere.
Not sure if this is a different bug, but I still get crashes after closing Minecraft. Not sure if it makes a difference, but I am playing on Apple silicone (M1) and thereby running Minecraft java in emulation mode.
Seems like a local network issue on my side. For whatever reason, Microsoft pages (or at least part of them) seem to be inaccessible to me. Using a VPN the launcher starts up fine with my Microsoft identity as it should.
Issue can be closed as the problem lies elsewhere.