Flew in to YYZ last night from LGA. Sat on the tarmac for 45 minute after landing while we waited for a Jazz EWR flight to vacate the gate and depart. After we got off we were held at the top of the stairs to customs for 10 minutes while it "cleared" and then were allowed down the escalators. Customs was a zoo but fortunately didn't have to wait too long with Nexus. I forgot YYZ didn't have sterile transit - having to exit and re-clear security is a pain. Both flights YYZ-LGA and LGA-YYZ were full - wonder if that was due to the long weekend or it's consistent across the board as "post-covid" summer travel ramps up?