Samsung Galaxy A5 (2016) — Samsung A5 2016 Nougat battery draining too fast...

Hello everyone, I have the following issue on my phone:

I only use my phone to do some regular whatsapp chatting and play a game... when sudently after unnistalling the game, I noticed that my battery was draining super fast despite not doing anything at all with the phone.

So I charged at 100%, and noticed that with all apps closed, he could only stay up for 24 hours?!??!

I decided to factory reset my phone, installed all my everyday apps again, and at 100%, my phone marked 50 hours, perfect!!

Then, now at 100%, he does only 38 hours, and I haven't done anything!!

Please help me... this makes no sense