Sony

Sony gets a high bar in our listing of toxic Android vendors, as historically Sony introduced the first very effective non-standard background process optimization and opened Pandora’s box.

It is called Stamina mode, and it instantly breaks all background processes and all alarms if enabled.

Basic setting

Stamina mode

Never use Stamina mode if you want your device to do something useful when not actively using it. Despite the official description, it does not affect only mobile data and WiFi, it also terminuates any background processes. Stamine mode can be find (and disabled) at either Battery section or Power management section.

Older Androids

Newer Androids

Advanced Setting

Adaptive battery

Adaptive battery was reported on Android 11, but it can be present on earlier versions too.

Power-saving feature

The app you need to run in the background needs to be set as Excepted from Power-saving feature.

System settings → Apps & Notifications → Advanced → Special app access → Power saving feature

Switch Pomodoro app to Excepted

Battery optimisation

Try to make your app not battery optimized in Phone settings > Battery > Three dots in the top right corner > Battery optimisation > Apps > Pomodoro app.

Source: dontkillmyapp