I hope I've fixed this issue on my 2020 EX, but there's one scary part that I haven't seen mentioned in all the posts here and elsewhere regarding the "random" occurrences of the alarm going off. I live in Florida. It's really hot here in the summertime. I had to go into a building for a few hours. I kept hearing a horn honking in the parking lot. I went outside and realized it was my vehicle doing it. I had left the windows cracked. I cycled the door locks and went back inside and it did it again a little while later. I went back out, cycled the locking system again, and went back in. After a few more times, I started worrying that this was somehow related to the amateur radio equipment I had installed and deliberately left operating while I was inside (the vehicle radio acts as a repeater for my hand-held radio) so I shut that off. The very last time I came out to deal with it was the scary part... Not only was the horn blowing, but the tailgate/liftgate had opened!
After reading the posts here, I do believe it was the ROA system at work (for the horn honking) and I have since disabled that (I haven't had a chance to check it yet but I feel pretty sure it will have stopped the problem). I started wondering about the tailgate issue. I wondered if that was a "last resort" action to hot weather and not responding to the rear seat occupancy alarm fast enough. Did the vehicle sense how hot it was inside and open the tailgate to try to reduce the interior temperature, given that it "thought" there was an occupant?
I called the dealership when this (the horn honking part) happened again (before I found the fix) and they had no clue - they'd never heard of any alarm "randomly" going off. I happened to find this thread here while I was on hold at one point with them and told them and they agreed that it might be possible (I didn't get into the tailgate issue since they didn't even know about the horn). I disabled the ROA system on the spot. I'm just wondering if anyone else has had the same tailgate experience.
Gil Chapin