As found out by @lpirl, the problem is the missing dtb file after the upgrade.
I recovered the rk3328-nanopi-neo3-rev02.dtb file from a different sd (but you can extract it from older images), and I copied it in /boot/dtb-5.15.25-rockchip64/rockchip. Check that /boot/armbianEnv.txt is pointing to that file (mine has the line "fdtfile=rockchip/rk3328-nanopi-neo3-rev02.dtb")
