

This is the command I used after unlocking the luks device in a rescue environment and confirming it not mounting further:
sudo btrfs rescue zero-log /dev/mapper/luksroot
After that, I could mount again and boot.
Here’s more info on the command, to verify advice is sound: https://manpages.debian.org/testing/btrfs-progs/btrfs-zero-log.8.en.html#zero
EDIT: For me it didn’t happen during an update, btw. You might still need the chroot approach to make the system bootable again.
How is trader defined? Is it a developer that’s selling apps or also one that’s just providing it for free?