I forgot which state does it, but there is at least one which intercepts all web traffic and runs it through MitM Proxy’s. I believe it’s citizen are forced to install their root certificate too.
Maybe you're thinking of Kazakhstan. Important to note that citizens had to install a root certificate for this to succeed, and even Then major browser vendors took action to invalidate it.
https://en.wikipedia.org/wiki/Kazakhstan_man-in-the-middle_a...