Found that the new #RaspberryOS based on Debian12 sets the memory page size to 16kB (from the default 4kB) which breaks a bunch of apps including jemalloc (used in Fulcrum - how I found out), btrfs, all android apps, etc.: https://github.com/raspberrypi/bookworm-feedback/issues/107
Check the value used with:
getconf PAGE_SIZE
Be aware if you are using a new image (default for the Raspberry Pi 5) the solution is to place the line:
kernel=kernel8.img
to the beginning of /boot/config.txt and restart the RPi.
Let us know if you have any thoughts on why we shouldn't use the kernel8.img on the #Raspiblitz by default: https://github.com/raspiblitz/raspiblitz/issues/4346