This happened to me with my BMW G01 X3, the seat mat sensor was not functioning properly and kept saying there was no one in the seat and airbag will not deploy. Odds are the dealer won’t look at that first, but I would request it.
I had a similar problem on my Ice Macan, when a pasanger got out of the car and I was continuing my travel the car would constantly beep because the passenger seat belt was not fastened. It was clearly a seat sensor problem but the Porsche dealership would not fix it as it was only a neucence.