My Iphone 14 Pro max Battery is degraded to 99 after 2 month of use

Not unusual at all since you can expect things to decline an average of about 1% a month. That's an average though. Some months, the battery may not decline at all, then decline 2% the next month after that.

After a year, the battery will be in the 88-90 range.

The typical Apple Battery lasts about 2 years. when the Battery Health reaches 80%, it will be time to make an appointment at the nearest Apple Store for Battery Replacement... take a look at this link...

Batteries - Maximizing Performance - Apple