Take a look at this Reddit. You could do some troubleshooting on your own by locating and removing the DCM fuse. Depending on year and options, you may lose some speakers, hands-free mic, and other things. But, if it stops draining the battery, at least you'll confirm that the DCM is the culprit. Cost to replace the DCM, along with alternatives, is contained in that thread.

edit to add: look in the engine compartment's fuse box for this fuse and remove it:

Thank you!!

We talked to the Subaru dealership today and they are very aware of the problem. They are replacing the DCM free of charge. We will see if the problem continues!!