I upgraded to 6.1.75-vendor-rk35xx and now my m2 ssd is not recognized anymore and the system is unresponsive and unstable. Once I remove the ssd, I am able to use it again.
I tried to revert to a previous kernel using armbian-config but that didn't work.
Here's how I reverted back to an older kernel:
sudo apt install linux-dtb-vendor-rk35xx=24.5.2 linux-image-vendor-rk35xx=24.5.2
sudo reboot
The system is stable again, including pci ssd.