Battery issues fixes?

We own a 2021 Subaru Outback XT. Often we garage it in a lot and the key is often in the car. When the battery burned out after 2 years, the dealer said the key can’t be in the car but it should be ok to leave the key on the windshield. 2 years later, the battery burned out again.

Has anyone used a Faraday bag or some low tech container to block the signal from the key fob to the car? Is it really the key fob communicating with the car that’s the issue? I’ve seen discussions here before about the battery issue and I assume it’s not been resolved. Thanks!