If I'm not mistaken, Reflector is the kind of the tool that picks mirrors based on different aspects, not just by which is fastest or close by. And if my memory serves me right, it actually picks mirrors based on their sync date with the upstream rather than speed by default.
You might want to check your configuration and set it to prioritize the mirrors based on the aspects you want.
I see. Much more complicated algorithms involved. Now I actually stop & disabled reflector and manually picked some local servers. Now I’m seeing 50mb/s and I feel totally dumb lol