Is that an assumption that the car goes offline (it should really be asleep) because you see no battery drain or are you seeing it go offline via some other means?I wish I could tell you; but repeated tests show that the car goes “offline” with very limited battery loss with no logging apps, and does this “online/offline” pattern with excessive loss even with only TeslaMate turned on (I checked and am using the last version, I did this after revoking all the API keys as well). I am as dumbfounded as you are…
You should raise an issue with Teslamate on their Github page. If Teslamate is causing your car to cycle between online/offline then there is something wrong. Not to rub salt in the wounds, but my car and lots of others sleep fine with Teslamate running, ditto Teslafi users. Worth getting it checked out as there may be something in the logs that can help you identify the root cause.