One USBC port stopped working after intermittent failure, PPP001

I have a Macbook Air M1 Late 2020 (MacBookAir10,1 - Z124000DESA/A).

It only has two USBC ports, I'll call them upper and lower. The lower port has been intermittently cutting out for a few months now. I usually use my upper port for my external SSD, and in the lower I have either power, or a hub with power+mouse+hdmi when I'm working with my second screen. I always thought the problem was just with the hub, but as of today the port stopped working completely, and doesn't work regardless of what I plug in.

Tried safe mode, no difference, and tried diagnostics which said PPP001 ("There may be an issue with the power adapter.") when I try it with no charger plugged in, or with the charger plugged into the lower port, but no issues when I have the charger plugged into the upper port. Seems like a misrepresentation of the actual error but I guess it's just a quirk of the diagnostic suite.

There's no apple shop in Vietnam, where I live, but I have a fairly reliable repair place in my city which is where I originally bought this mac (just out of warranty, of course). But I'd prefer to know more about this issue and diagnose it fully myself before I take it there (or if it's simple, maybe fix it myself). I found some old links about replacing ports in much older macbooks but no resources that match my device and situation, beyond "take it to an apple shop".

Side note: I feel like this issue is probably caused by the lack of electrical grounding in my house (indeed, in the entire country tbh). If I'm using my macbook alone with only its charger, I don't usually have problems (I assume low power usage + some advanced tech in the charger), except as of today in the lower port. But if I'm connected to my external monitor by HDMI, I get shocks touching my mac, and especially the hub. I feel like this can't be good for my devices, and wouldn't be surprised if it has fried my usb port. I've lost lots of other devices in similar seeming circumstances, in this house and others. I don't really know if there's anything I can do about this, since I don't own my house and my landlord (who is an electrician, lol) doesn't see the value of grounding and has basically no house in the entire country has it anyway. So yeah I just wanted to mention this in case anyone has been in a similar situation and has a solution.

Anyway thanks in advance everyone.