MacBook Pro doesn't charge

I just bought a 16" MacBook Pro. Since two days after I bought it, there's an issue where it doesn't charge until I unplug the USB-C cable from the adapter, plug it back in, then unplug the charger from the laptop and plug it back in. Sometimes I can get it to charge by going through the same process but instead of unplugging the USB-C cable from the adapter, I unplug the adapter from the wall -- the former method always works, though. I have no idea what's causing this. I've tried plugging the charger into other walls and extension cords, but the problem remains.

I suspect that it might have to do with the fact that right before this problem started, I had used an off-brand extension device that would plug into the USB-C port on my MacBook and function as a magnetic port for my charger -- basically imitating MagSafe with a USB-C charger. I used that once and this problem has been happening ever since. But I'm not entirely sure that's what's causing it.

Any ideas?