Hmm... true that, but your encoder is a bit different from the one in tutorial so who knows how it works...
From aliexpress page it seems that it's mainly for Arduino and older ones are mostly 5V so that could be the reason for 5V marking on it.

I'd probably try to connect it to 3,3V and see if it works. Lesser voltage shouldn't harm gotek, and you can power gotek on without any computer connected and see if it reacts to encoder.

I haven't use these so far, only "plain" encoders so there's also that option, desolder it from this PCB and solder it plainly. Or remove all these SMD components and solder it like it was plain version.

Altough if you have dupont cables I'd first try to see if it works via 3,3V, if it does job's done, if it doesn't, solder fun.

Thanks a lot! It works and there is no smoke at all 😀