My father purchased a Galaxy S7... and within a year and a half, it was so slow, that we were just trying to eek it along until the 2 year mark. A software reset didn't do the trick either. Turns out the chip inside (Snapdragon 820) was pretty notorious...
We then purchased a Galaxy Note9. And same story - within a year and a half, super inexplicably slow, closing apps at random, eeking it along until we can get a new phone from Verizon. Then it started dropping phone calls after a botched software update. Plenty of complaints on the forums - no response from Samsung. Software resets had no effect on that issue if you were effected. At that point, replacing the phone was a business necessity. [And my dad isn't doing anything intense - 90% of his work is in Outlook and the web browser.]
This time, iPhone 13 Pro Max. We'll see how it goes. Been almost a year, performs like ever. Seems to be holding up...
On that note, we were also angry at Samsung because we bought a Samsung kitchen. The Stove broke after a year, the replacement also broke, switched brands. The Dishwasher lasted 6 months... and broke, switched out with Bosch. The Microwave hasn't broke... yet... but the electronics are in the door and the repairman warned us those only last a few years before the circuit board snaps from the impacts, so be delicate. At that point we swore off Samsung for everything.
EDIT: If you are wondering if this was due to battery problems... a battery replacement on the Note9 made no discernible difference.