Initramfs mounts btrfs partition instead of root subvolume

I have a setup where initramfs fails at the initrd-switch-root.service since it can’t find a valid sysroot. The cause for this is that somehow the btrfs partition itself is mounted unter /sysroot which gives e.g. /sysroot/root/etc/os-release.

Where do I tell the initramfs to either switch-root into /sysroot/root or to mount the btrfs subvolume to /sysroot?

The grub configuration points to the UUID of the root sub volume and also seems to take btrfs into account.

I’m happy to edit in any necessary files / info needed.