Hi. One week ago my Tab S4 received the March 2021 security patch and the battery has been draining from that day. It consumes around 2.5%/hour when being idle so a 100% charge would only last 40 hours, instead of 10-12 days. I have wiped the cache partition and have followed all the steps to optimize the battery but it's the same. What I have noticed is that if I activate the airplane mode, the battery is good again. I am pasting two links where you can see that the Galaxy S21 had the exact same problem with its February security patch. My Tab S4 is old so maybe that's why nobody else has noticed it yet.
I am having this exact same problem on my Tab S4 after that update! My S21 gets a lot more use and doesn't generally sit idle for long when it isn't charging, but I have also noticed that the battery has been draining quicker on it, too.
Hi. Yesterday my tablet received the March security patch again and it was perfect during the day. But in the night I updated the apps and, during my sleep, the battery began to drain exactly as before the second March security patch. I wiped again the cache partition and did all the steps that Samsung recommends, but the problem has returned exactly as before.