I don't know who needs to read this, but apparently there is a pretty widely used DNS blocklist for PiHole (or in my case Technitium) that currently seems to block google.com and github.com, and probably some other sites too, for... I don't know which reason. I just thought my DNS broke, but no, the filter is just going crazy right now. Just so you know in case you're running into the same issue as soon as your AdBlock updates its lists.