Any experts on Android tablets around?

My tablet, Samsung Galaxy, is like 4 years old and since the last system update, the battery is draining, even if connected to the mains.

Tried developer options, stopping apps, deactivating some of them, charging in flight mode, restarting ... no real joy. It works for a week, and back to square one.

Chargers as such are new and working fine. Not doing any gaming or watching video clips all the time.

Any ideas? Bar buying a new tablet? I can't really afford that.

Thanks

Probably best to wait a while and see if the update gets patched.
Or its possibly time for a factory reset. It sounds like the BMS (battery management system) If you've tried the app disabeling route with no joy.

Have you tried it in 'safe mode'? if it is ok in safe mode, then it's almost certainly an app thats not compatable with the update. good luck Larsi.
And remain calm.

PS not an expert.

I've experienced the charging cables reversing the charge to a discharge, so good quality cables are essential. I have no idea why this happens, but I've had it happen to two devices. I bought new good quality cables and fixed the problem in both cases.

Google it. Usually the fast track to finding solution and if others have the same problem after the update.
If you can find a contact thing, contact Samsung about it.
And check if it's possible to roll back to before the update. (restore point?)

Updates can sux. Been there too a few times.
My girl's Samsung Android phone does a weird thing since last update: when she's on the phone and receives another call, she gets disconnected from the call she's on.
Both she and my son -who's quite the expert- couldn't find a way to change it, and it was never like that.
Just a FU update...

Good luck!