Synaptic "override" of latest installed Kernel with lower version during update

[ironfoot]

That's weird. Anyway, if you don't specifically need kernel 6.8.0-45, I recommend you install the HWE kernel and keep it updated automatically.

Ubuntu MATE 22.04.5 Released

As @guiverc said, You don't have to install new HWE kernels manually, @ericmarceau, this is enough to track them: sudo apt install --install-recommends linux-generic-hwe-22.04 https://ubuntu.com/kernel/lifecycle

The current HWE kernel in Ubuntu 22.04 is 6.8.0-52.