Hi Estevão,
There shouldn't be a significant difference in power drawn by the screen even for aftermarket OLED displays. If you'd gotten an LCD replacement then yes, you would see it take more watts to run due to the need for a backlight, but the OLED shouldn't be giving you problems.
Personally, I'd go ahead and swap out the battery again; look for a different vendor this time. You don't necessarily have to spend a lot; I've had pretty good luck with aftermarket batteries overall, but you never quite know for sure how long they've been sitting on a shelf. There are people selling new batteries made in 2019, which you definitely don't want.