Ok, so just 12h. Sentry alone couldn't explain all of that. You said it was off but if you turned it off from the mobile app, it might have been on still. That might have explained 3-5%.
No conditioning in the morning, good.
The other aspect is that it's getting cold outside. Teslas use two (or more) separate SOC values. Here's what TeslaFi says for my car this morning:
View attachment 867020
My current soc is 54, my target for charging is 56. However look at the blue 53 with the snowflake. In the car, it is 53% that would be displayed, and probably in the mobile app as well. My battery still contains 54% of its capacity in energy but the car estimates that at its current (cold-ish) temperature, the battery will only give me back 53%. It was 10C last night and it's currently 14C outside, really not that cold. It's possible that your battery got cold last night.
Sometimes the car will show the blue snowflake and the battery "drawing" that shows SOC might have a blue section, but not always when it'S not cold enough.