I currently have s21 ultra and s25 ultra is about to launch. I was researching online until what year will the s21 ultra keep getting updates (2026 or 2027) after i have received the android 15 (this phone has supoort for 4 OS and 5 yrs security patch). I do feel some jitters, animations break out while daily usage and battery is not in good condition ($100 for new battery) but it can run for 2 more years if it will get updates. So I am confused wether should I upgrade to S25 ultra or upgrade its battery and run it for 2 more years.
Try a factory reset; that might help with jitters and broken animations. I suggest researching a certified store to replace your battery. You can ask for prices. Honestly, I'm not sure if Samsung will give you much in trade-ins.
You may want to go back and do a bit more research about the S21s. The S21 series launched with Android 11 and Android 15 will be the last OS update (they were promised four) and then the last security updates are going to be sometime in 2025. So, you do not have two more years of updates.
