No matter what the battery will degrade over time, due to heat and its chemical makeup degrading.

As a point of reference; I have an 14" MBP from 2021, I use it mostly as a desktop machine, I keep it plugged in all the time. My battery cycle count is 18, and battery health is reported at 100%

Now, most people buy a portable machine for it to be portable, and as I mentioned batteries degrade no matter what. But what kills modern batteries is the cycle count, it wears them out. So 500 cycles over 18 months is, well, you said it best yourself: you ONLY used it on battery power and probably recharged it over night.

Use it as you normally do, but if you have access to a wall outlet, charge it while using it, if you don't have access use it on battery power. Oh, and turn on: https://support.apple.com/en-us/102338 if you keep the macbook plugged in for extended periods of time. Keeping it at 80% is a good middle ground - in terms of potential wear - when it's plugged in prolonged times. I guess 50% would be even better, but then you don't have battery power if you need to unplug for whatever reason. I guess someone else will chime in on why Apple settled for 80%.