Factory Alarm is going off for no reason

I would start with the battery. Check the battery terminal connections to ensure they are tight. Either a bad battery or loose terminal connections can cause the alarm to go off for no apparent reason.

Came across this post a few times while dealing with a random alarm the last few months(multiple times a day). A few notes in case someone is reading this from the same situation I was:
1.If you use the actual key blade (take it out of the fob, put it in the driver door, and turn) it will lock but not arm the alarm system.
2 .Buy a scanner. (I think I searched “gm tech 2” on Amazon.) I bought one specifically listed for “gm” for about $150. Or get it scanned at a dealership, which might cost more than a scanner, but it’s simpler if you’re not tech inclined. On scanner, under BCM there is a “content theft alarm” that lists the alarm trigger history(my scanner shows the last three). Mine listed “hood” and that is where the problem was. Latch was sitting too low and was switching the sensor from open to close at random. Hope this helps someone. Get it scanned, don’t waste your time on a wild goose chase.

This is interesting. I am not experiencing this issue (knock on wood), but one of my rear defroster tabs broke off maybe three years ago. I took the opportunity to break the other one off, and then tucked the wires behind the trim panel (hated the exposed wires bouncing around, and I literally never have a need to use the rear defrost). Never had a weird alarm problem.

Mine was going off at the same time every night for a while. I figured it was the neighbor activating the massaging seats in his Lazy-Boy recliner and pushing the buttons on his ROKU remote control! LOL

Check that the rear defrost wires haven’t become loose or unsoldered.

Mine went off the other night while camping. I figured it was the curious elk bulls that we had spent the evening watching and being watched by.

Last time I had an issue with this, oddly enough it was an issue with the ignition switch. GM ignition switches cause some wonky issues.