After the update of 27-09-2021 in Asus TUF FX505DY, the Battery Health Charging feature in MyAsus automatically turns it to Maximum Capacity randomly. I haven't seen any specific pattern but yeah it has started to happen.
Armoury Crate UWP App 126.96.36.199
ROG Live Service 188.8.131.52
AURA Service (Lighting Service) 3.05.18
Armoury Crate service 4.2.10
Asus Framework Service 184.108.40.206