MacBook battery health

Nothing to worry about. Batteries are consumables and they all degrade over time. The metric to watch is remaining capacity. When it hits 80% Apple advices you replace it.

Trying to micromanage your battery is a waste of time and effort, turn optimization ON and let the Mac handle the battery's health. Charge it when needed, use on battery as you need to and let the Mac do the micromanaging.

Yes

Batteries are considered Consumable Products.

Over time it will degrade to a point where it needs to be replaced.

The usage is normal as the capacity will go up and down all the time and never stay always at 100%.

Apple Batteries are rated for 1000 Full Battery Cycles and / or 80% Capacity