I figured out what was causing my particular battery problem, and it was kind of a strange phenomenon:
Looking at the battery chart in settings, I noticed that the excessive battery drain (3-5% per hour) always occurred between 8:30 AM and 6 PM, and only on days when I was at the office. I assumed it must probably be caused by a weak signal at work or something related to the building itself, and I just had to deal with it.
By accident (or dumb luck), I found out what it really was: with my 12 Pro Max, I was using a wireless charging stand on my desk, where I also put my 14 Pro into every morning, simply out of routine. Charging never worked though, probably because the case I have on my phone (UAG Plyo) is too thick. I never cared about it not charging anyway, it just looked neat sitting there.
The other day I left the office to grab lunch at noon. When I came back, I forgot the phone in my jacket. When I looked at the battery graph that evening, surprise, it stopped dropping exactly at noon, and that's when it hit me that that charging stand might have been the problem all the time.
The next day I just laid the phone on the desk, et voilà: everything was fine - it only used up 4-5% of charge throughout the whole day. Now my battery is still at 90-95% every day after being off the charger for 15 hours.