Plymouth shows stacktrace for no apparent reason

I've got a beautiful seamless startup experience with Arch & KDE Plasma 6.1, thanks to Plymouth. But after recent updates (I believe to kernel 6.9.x), the splash screen is interrupted by a stacktrace. The trace doesn't seem to offer any meaningful information on what went wrong. Also, Plymouth works fine regardless. The stacktrace doesn't show up in logs, so I've made a photo of it - ignore the 'no key available' message, I was hitting return to see if it froze, but it didn't, it was still waiting for my passphrase: Then there was some mention of Plymouth exiting abnormally in journalctl:

Jul 23 12:21:31 archlinux systemd-coredump: Process 311 (plymouthd) of user 0 terminated abnormally with signal 11/SEGV, processing...
Jul 23 12:21:31 archlinux systemd-coredump: Due to PID 1 having crashed coredump collection will now be turned off.
Jul 23 12:21:31 archlinux systemd: Starting NVIDIA System Management Interface...
Jul 23 12:21:31 archlinux systemd-coredump: Resource limits disable core dumping for process 311 (plymouthd).
Jul 23 12:21:31 archlinux systemd-coredump: [🡕] Process 311 (plymouthd) of user 0 terminated abnormally without generating a coredump.

I also tried adding the kernel option plymouth.debug. This doesn't seem to provide much more insight. There is an interesting thing, it has a lot of mentions like this:

00:00:46.600 ../plymouth/src/libply-splash-core/ply-terminal-emulator.c:989: terminal escape character: carriage return

This suggests I'm hitting return? Because I was not. Here's the entire log: https://pastebin.com/rpvnkgZ3 There are also some mentions of a timeout. This is interesting, because when I boot, the Plymouth splash screen comes up normally, in proper resolution etc., but after a few seconds, it cuts to the stacktrace. Then, when I enter my passphrase, it continues to boot normally. Curiously, if I use the plymouth.debug kernel option, it fails to boot, it then hangs on 'Reached Target Graphical Interface'. Any ideas what this could be? I've tried reinstalling Plymouth, but that made no difference. I also rebuilt initramfs (multiple times, obviously to get the debug log), also no difference.