Hi,
There are some discussion in
Avoiding apt upgrade from Jetpack 6.1 to Jetpack 6.2
Could you try this to mark the packages:
$ sudo apt-mark hold nvidia-l4t-rt-kernel nvidia-l4t-rt-kernel-headers nvidia-l4t-rt-kernel-oot-modules nvidia-l4t-display-rt-kernel
So that sudo apt upgrade does not refresh the self-built RT kernel.