Seemed like a parasitic draw but pulling fuses and using a multimeter verified idle draw at 30 milliamps which is within spec. If you find high like a few hundred milliamps you can start pulling fuses to narrow down offending item.
In the end it was a bad a battery, but was difficult to get the warranty replacement because it could be charged and work again so long as you ran it every day.
It's relatively easy to verify parasitic draw and make sure it's in that 30 milliamp range, with even a cheap multimeter by disconnecting negative and running through multimeter. Tricky part with modern cars is getting it to go fully to sleep, anything can trigger wake up (like opening the door) and it can take a few minutes for it to fully sleep to idle draw.
One such Camry in our extended family was parked for a few months and the battery failed. We got an expensive OEM replacement and tried to make sure we drove the car every week or two. It failed again in just under three years. Meanwhile, we have an entry-level Audi that also often gets only a short local trip every week or two. It is still on its original AGM battery after 6 years, and this one has to actually start the ICE.
So, I am disappointed to find that Toyota engineers could not be bothered to apply whatever basic power management logic the Audi folks did to protect the battery. Worse, the Camry has this big NiMH traction battery, and I would have imagined some clever backup strategy to infrequently top-up the 12V battery if parked too long, so it would be reliable.
In the end, I gave up and installed an old-school battery cut-out switch, so we can just disconnect the 12V battery if not planning to use the Camry for more than a few days. Every time I operate it, I'm giving the Toyota engineers a rude hand gesture in my mind.
It should be feasible to monitor voltage levels and rates of change and signal an error condition rather than silently destroy itself...
Everything I've read online about the issue points to the STARLINK system, and the common wisdom in this thread and elsewhere is to pull the DCM fuse. Unfortunately, my Forester has no such fuse, so I'm at a loss what to do with my car.
It's so frustrating, because my wife has a Subaru Crosstrek of the same year that has never had a battery problem, even with the OEM battery. She has a base model without any additional "upgraded" electronics, so that's the likely culprit in my case. I'm currently on my third or fourth higher CCA battery and had to jump it again a few days ago.
I haven't taken my car to the dealer for the parasitic drain issue, but previously tried to get dealership service for an unrelated entertainment system issue related to USB media playback freezing up the entertainment system. That fix was unsuccessful, and I have no faith in Subaru mechanics being able to diagnose and fix a potentially more nebulous battery drain issue. It doesn't help that the dealership is now 45 minutes away, so I'm not interested in wasting even more time on a hit and miss solution.
Ironically, I bought Subaru because reliability was my number one concern when purchasing a vehicle, and I'm not sure I would do that again.