I’ve had a OnePlus 9 Pro since around when it came out in April 2021. Around 6 months later I installed AccuBattery and started trying to keep my phone between 20-80% battery. I still charge it to 100% sometimes, like when I think I won’t have access to a charger or will be out for a while, but generally I stick to it. It is also good to do a full charge (<15% to 100%) once every few weeks because it helps the battery stay calibrated and give accurate percentage readings.

In the 3+ years since then, my phone’s reported battery health has gone from a little over 90% to ~83-85%. I also almost exclusively use the 65w fast charger that came with my phone (I’m impatient) so that might be hurting my battery a bit more also. Here’s the graph of battery health over time that AccuBattery shows me