Sometimes it depends on the way data is transferred and also occasionally a rogue app can cause more battery drain than it should.
If the battery doesnt perform as well as expected it is always worth checking the battery settings to see what may have been causing the issues. Example below of the battery during today for me.
For your use case perhaps you have a good set of apps that are not causing the drain your mum was seeing.
Smiley
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User: Smiley
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My life is full of positives and negatives. I’m an electrical engineer.
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