I'm not sure this is entirely the case, though probably partly so. I think they do track known VPN servers, or suspected therein, and closer to congress session

I'm not sure this is entirely the case, though probably partly so. I think they do track known VPN servers, or suspected therein, and closer to congress sessions cut those off. I had a number of self hosted setups used by a few people that would get cut off at those times only to come back on later.