Linux 6.7.3 + 545.29.06/550.40.07: ERROR: modpost: GPL-incompatible module nvidia.ko uses GPL-only symbol '__rcu_read_lock'

The error occurred on my Debian 12 also well.
Driver: 525.147.05 (from Debian repo)

It happened when updating to kernel 6.1.0-18-amd64.

On Debian, upgrading to kernel 6.5 (from backports) fixed the nvidia issue when using kernel 6.1.0-18-amd64 and dkms:

sudo apt install -t bookworm-backports linux-image-amd64
sudo apt install -t bookworm-backports linux-headers-amd64