Thanks for the thread, but I think it doesn’t really help.
My power supply is AF-compliant and it also protects non-POE devices.
And it looks like, the power supply is enough (no throttling etc.).
Also the splitter SHOULD be, at least there is a sticker on it that says “IEEE 802.3af/at”
However, its a cheap splitter from amazon, maybe a better PoE Splitter, a PoE Hat or a ferrite core around the USB cable may help?