Also don’t underestimate the fact that OP has a new phone and is trying stuff out. The screen is usually one of the biggest power drainers in phones, so it could be that it just isn’t a fair comparison. I wouldn’t be surprised if the phone is just unlocked and awake more in the first few weeks compared to a phone you’ve been used to.

Nice, great step! Just in case: did you check if you have any forgotten “log in with facebook” linked applications? You might want to check them to see if you have configured an alternative login. If you’re not sure, I very strongly advise you to undo the delete while it is still possible, and go into settings to check for this. When you’re sure you’re all good, you can just delete the account again.