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You forgot to lock it.
I did the same years ago, I was emptying the car after a Christmas trip to in-laws and with all my hands full I thought I'd lock the car from the kitchen window once I'd put all the bags down.
I forgot to lock it and someone stole 2 pairs of prescription glasses, my (5th gen!!) iPod, and the proprietary cable to go with the iPod (the most annoying bit).
I was certain that I locked it and the thief performed magic, but occam's razor and that.
Had a flashback about 3 months later that I dropped the bags in the kitchen then ran to the toilet because I was desperate for a shit and then forgot all about locking the car.
Other than me forgetting to lock it (unlikely but possible) how can someone get in to my 2020 Skoda, rifle through the crap I leave in there, then get wildly frustrated at the lack of stashed away Rolex under the seats only to steal my iPhone charge cable in a fit of pique due to the aforementioned volume of crap and nothing else of note - without the car alarm going off?