Whoa, a thread actually about trees? Thank you!
Maybe some kind of gall? Hopefully just cosmetic and hatches a few bugs. Maybe I’m wrong, let’s see what other input you get.
At any rate, this time of year and in your area, that tree is definitely at risk of oak wilt if you start cutting. Really want to wait til November or later, when it’s dormant to prune it. Oak wilt is ruthless and it’s fast. By the time you notice some visible decline, it’s too late to do anything.