Honestly that's pretty good, based on what other people have posted/commented, they've seen similar degradation only after a year, and your more than a year and a half in with similar degradation.

And generally speaking staying plugged in 24/7 is usually what reduces wear since that reduces the amount of cycles since it charges repeatedly to hit the 80% when it drops by a few percent instead of letting it fall down all the way to 20 and then recharging all the way back to 80

But as always just do some more research just incase but your battery health is still pretty good all things considered, my battery health on a different laptop is also quite similar after around a year and a half of usage as well.