I guess as you said, maybe because mine is an iPhone? ????
I really noticed it. It went down (with all background apps closed) something like 3% within a half an hour. But that said also the Battery is now only at 90% remaining peak capacity. Already looking for a new Phone, but no idea what to get yet.
But not an issue, my friends have an old iPhone 7 which I can use and that is also the phone they tested (already bought) the new SIM card with.