Clear system cache on both devices and post up your battery stats so we can see what is happening. Some apps like Chrome and many social media apps are not fully compatible with Android 11.
cache cleared as a rule after every update. partition cleared after every update too. don't use chrome. every app i don't use is in deep sleep or disabled. battery stats only show basic usage (as in minimal percentage ) and don't represent the actual battery percentage decline. went from 15% to 2% just now I less than 3 minutes. s10e was my day to day phone and the battery lasted on average 2 days. do not have social media apps on my phone as I don't like them pillaging my photos and data even when I have not allowed those permissions, I use Web apps for them all.
What are you getting from a full charge now? Compared to the 2 days you say you were getting before?
If you do buy another Samsung phone, go for a handset with a SD processor. I've had s10, s20, compared to battery life on s10 lite is day and night difference for me! And it's has a 4500mah battery.
Until today my battery was fine but I have updated my S10plus this morning april security patch, looks like my phones battery losing a bit more than before the update
About 10 hours battery life. Even if the screen is off. Have been trying everything. Nothing helps at all.🤣 UPSM is even worse. Literally loses 1% per minute. Have uninstalled everything and re installed. Have had all sensors off. All connections off. Wiped all caches. Etc. Only option left is a factory reset. But given even people who've just bought s21s are posting about 6 hour battery lives I just can't be bothered. And let's be honest, I shouldn't have to.