I updated to Android 12 less than 2 weeks ago. With my normal usage, I got 3 - 4 days out of a full charge. If it sat unused, a full charged lasted over a week. Now I get less than 24 hours, even if I don't use the tablet and it's sitting with the screen off, (I NEVER use the always on display) all apps closed, and the case closed. Several times I've tried to use the tablet first thing in the morning and it's off because the battery went to 0%.
Today I went from full charge at 9am to 17% at 9pm without using the tablet until just now. It was flat last night so I charged it and unplugged it this morning after making sure it was full. It sat untouched all day. My tablet is less than a year old. This is unacceptable and has to be fixed.
I'm having the exact same problem. Had it on idle, locked screen and case on at 74%, the next day picked it up to make some notes and was scared for a sec the device wasn't turning on: 0% battery.
My tablet has like a year of usage.
Have 3 Samsung Tablets S7 and two S6 Lite. Installing updates on s6 lite reduce battery life to less then 24h even without using it. First s6 lite was updated three weeks before second , and I can confirm it just happen after update on both. Looks like Samsung trying to force people to upgrade for newer tablet....