https://wccftech.com/ios-14-5-enables-dual-sim-5g-on-iphone-12-along-with-smart-data-mode-improvements/

Apple has improved how 5G works on the iPhone 12 lineup of smartphones and has tweaked Smart Data Mode as well.

iOS 14.5 is packed with a ton of new features, but if you have an iPhone 12, iPhone 12 mini iPhone 12 Pro or an iPhone 12 Pro Max, then there are some 5G improvements you should care about.