We now have one potential explanation for why the new iPhone 12 models drain battery more quickly than they otherwise might. Although Apple is using a Qualcomm Snapdragon 5G modem, it is the older X55 component from last year, rather than the newer X60 modem released earlier this year.
https://www.notebookcheck.net/Apple-s-iPhone-12-range-uses-Qualcomm-s-superseded-Snapdragon-X55-5G-modems.498878.0.html