Debian 12 - 6.1.0-18-amd64
sh /usr/src/linux-headers-6.1.0-18-common/scripts/modules-check.sh /var/lib/dkms/nvidia-current/525.147.05/build/modules.order
make -f /usr/src/linux-headers-6.1.0-18-common/scripts/Makefile.modpost
sed 's/ko$/o/' /var/lib/dkms/nvidia-current/525.147.05/build/modules.order | scripts/mod/modpost -m -o /var/lib/dkms/nvidia-current/525.147.05/build/Module.symvers -e -i Module.symvers -T -
ERROR: modpost: GPL-incompatible module nvidia.ko uses GPL-only symbol '__rcu_read_lock'
ERROR: modpost: GPL-incompatible module nvidia.ko uses GPL-only symbol '__rcu_read_unlock'
make[3]: *** [/usr/src/linux-headers-6.1.0-18-common/scripts/Makefile.modpost:126: /var/lib/dkms/nvidia-current/525.147.05/build/Module.symvers] Error 1
make[2]: *** [/usr/src/linux-headers-6.1.0-18-common/Makefile:1991: modpost] Error 2
make[2]: Leaving directory '/usr/src/linux-headers-6.1.0-18-amd64'
make[1]: *** [Makefile:250: __sub-make] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-6.1.0-18-common'
make: *** [Makefile:82: modules] Error 2
EDIT - RESOLVED thanks @felipsmartins!! booted on 6.1.0-15, then
sudo apt install -t bookworm-backports linux-image-amd64
sudo apt install -t bookworm-backports linux-headers-amd64
sudo apt purge linux-image-6.1.0-18-amd64
sudo apt update && sudo apt upgrade
rebooted on 6.5.0-0, nvidia installed, life is good again.