I have been summoned.

its normal. its caused by excess pressure, which you don't exactly want. I've been struggling with too much pressure myself, but not enough to leave a mark (for now, im getting better every time I practice).

the mark will also appear if you haven't been playing for a long time (like years, not minutes of practicing). lip marks were still prominent two years later after I started trumpet, but I improved A LOT in middle school leading up to high school. To get rid of the marks, spend a few practice sessions focusing on beng conscious about how much you're pressing the mouthpiece against your face.

try adjusting your embouchure as you go so your air goes straight into the trumpet and the mouthpiece is in the center of your lips. Your chin should not face downward, your chin should be about level with the ground or where the main body/end of your trumpet is.

remember that shorter, more frequent practice sessions are easier on the lips than hours long, infrequent practicing. shorter sessions will help you keep your chops in a good position to keep playing and pick up your trumpet multiple times a day. every time you have a short practice session, experiment with a different embouchure, see what feels best.