Battery “unknown part issue” after update ios 15.6.1 iPhone Xr

After the update my iPhone XR battery whas this message and it will disappear after fully charging it and rebooting several times. Then in the middle of the day with 50% charge still on it reboots itself and drops to zero charge.

Battery health is 82%, I had no battery issues whatsoever with the previous iOS. The battery is 100% original since I bought it new that time and never have change it.

Apple support ask me to go service centre with possible fees but I think it’s not my fault that caused this problem.

underneath the graph of no error message about battery then reboots itself and then red bar at 12:53 with error message “unknown part”