If you downgrade jepack 6.X to jetpack 5.1.6 with sdkmanager you will end up with “nvbootctrl dump-slots-info :: Current version: 0.0.1”. Solution is to use jetpack 5.1.1 at first.
[ Problem updating to JetPack 6.0 using SD card - #9 by dlu ]
Stability of jetpack 5.1.6 looks good now.