2018 Subaru Outback tailgate opened, battery died

2018 tailgate open during the night. Result: dead battery.

It’s a known problem. Subaru insists it’s caused by owners hitting the button on the fob by accident. But one of the Outback forums mentioned a TSB that was issued in March of this year. https://www.subaruoutback.org/threads/2015-liftgate-opens-on-its-own.319514/page-2 The thread is about a 2015 but the problem apparently affects other years.