Usually a person would see major changes when moving from one main android platform to another i.e Android 11 to Android 12 for example.
So when on Android 11 when we get an update which does include the next new security Patch this also can include subtle changes you may not see or changes in the background such as device optimisation.
There are tips to help lengthen usage time's on a phone which are on the forum here , on tech sites and on YouTube however battery SoT and stats is a subjective topic as we all set our phone's up differently.
As mentioned the soc can have an impact on optimisation. Snapdragon is known to provide better optimisation than the Exynos soc in some cases.
Also over time a batteries output can shorten due to usage and the act of charging and discharging the phone.
Current Phone > Samsung Z Fold³ 5G.