Yes Tor usage by default is trivial to detect because the list of Tor nodes your client connects to is public. The EFF has a nice interactive graphic that shows

Yes Tor usage by default is trivial to detect because the list of Tor nodes your client connects to is public. The EFF has a nice interactive graphic that shows what different actors see if you use Tor [0] You can make that harder to detect by using a bridge. https://bridges.torproject.org/ https://bridges.torproject.org/ [0] https://www.eff.org/de/pages/tor-and-https https://www.eff.org/de/pages/tor-and-https