Okay thanks, so either only very old bootloaders are affected, or it it affects certain SD cards only.
@usr_9 @Cosmo2 if you are open for another test:
cd /tmp
wget https://dietpi.com/downloads/binaries/testing/linux-u-boot-rock64-current.deb https://dietpi.com/downloads/binaries/testing/linux-{dtb,image}-current-rockchip64.deb
dpkg -i linux-u-boot-rock64-current.deb linux-{dtb,image}-current-rockchip64.deb
/boot/dietpi/func/dietpi-set_hardware flash-uboot-mmc
reboot