Okay, the PR was also tested on Zero 3. While both use the same kernel, the Zero 2W device tree is a different one. Can you test the following on the DietPi system with the new kernel:
G_CONFIG_INJECT 'fdtfile=' 'fdtfile=allwinner/sun50i-h618-orangepi-zero3.dtb' /boot/dietpiEnv.txt
It should match the Armbian image you tested.
I pushed this kernel to our APT repo in the meantime, so in case you use the older kernel:
apt update
apt upgrade
or upgrade to DietPi v9.5 which was just released.