It was already clear that the iPhone 12 and iPhone 12 Pro would lose battery faster when hooked to 5G networks compared to 4G ones, but we didn't know how much. Well now we sort of do, thanks to Tom's Guide and their battery test - running a browser script at 150 nits and loading a new web page at 30 second intervals. Under those conditions the iPhone 12 lasted for 8:25 hours on 5G and 10:23 hours on 4G - that's around a 20% difference. The iPhone 12 Pro did a little better - 9:06 hours over 5G and 11:24 hours over LTE - again around 20% better. When compared to their respective...
Source: https://www.gsmarena.com/new_iphone_12_and_12_pro_lose_20_more_battery_when_on_5g-news-45906.php