I upgrade my mac OS to Sequoia Version 15.5, after use of few month my battery maximum capacity downgrade 99% to 96%. i'm not use heavy applications.
MacBook Air, macOS 15.5
The Battery Capacity jumps all the time and that is nothing new
It is when the Battery Capacity drops to 80 % or 1000 Full Battery Cycles is when one needs to be concerned
OP wrote " I upgrade my mac OS to Sequoia Version 15.5 "
You may consider updating to current macOS Sequoia 15.7.1.
Released September 29, 2025
My MBA M2 maximum capacity jump 99 to 96% after upgrade Sequoia Version 15.5
