Is it normal for my MacBook Air battery to stay at 80%?

Recently bought a MacBook Air M3, since day one got the MacBook I have always use it at home and always keep my MacBook plugged in and never unplugged. But for the past few weeks I notice my battery are always on 80% and said charging on hold( Rarely used on battery) but few days later it will suddenly self charging to 100% than few hours later it will go back to 80%.

I have also check my system info and notice power cycle count has went up to 3.

Just want to know is this normal, will it affect the battery health and MacBook it self, just little worry as I am new user on MacBook.

p.s since day one setting up my MacBook I have always put on batter on low power mode.

[Re-Titled by Moderator]