It also shows up like this ingame as well, like "Federated systems of %DefaultPlayerName" or in the scoreboard. Trying to edit name in lobby results in name turning red and reverting to %DefaultPlayerName.

Validating file integrity did not result in any files being replaced. I have not yet tested how this interferes with multiplayer.

Also as a side note, I cannot use "Join" button inside protected game lobby to switch to other factions. I'm sure it worked before.

After some slightly painful troubleshooting, restarting Steam fixed the problem. Seems like Steam Integration just was acting wonky.