Many of the tor relays are operated by intelligence agencies (this is known, and obvious otherwise). If you connect to one of those, your IP is logged somewher

Many of the tor relays are operated by intelligence agencies (this is known, and obvious otherwise). If you connect to one of those, your IP is logged somewhere forever. These same agencies, depending on your country, can probably know who that IP belonged to at the time instantly, or quickly enough. If the agency has a wiretap on the ISP's fiber, then they'll know even if you're not connected to one of their relays (you could use the unlisted bridges, but they probably know those anyway)