On iPhone, for the longest time, every browser has been forced to be Safari's engine underneath. Firefox, Chrome, etc are all forced to run Safari underneath.

This has caused many issues because Apple controls what can run in a web browser and that web browser (safari) is in no way up to date, or worse, selectively implements standards. I'm writing this in the hopes that it will publicly improve.

Since Safari is forced at an OS level on all Apple's iOS and iPadOS users, that's a place to start when it comes to choice.

On MacOS, Safari is actually pretty interesting - it can be much more efficient with battery usage than other browsers and unsurprisingly well integrated. It's nice to use on MacOS because there is choice.

I understand there maybe concerns about security, but also will come out is likely that safari enjoys some OS level integrations that other browsers probably won't be welcome to, similar to the Internet Explorer/Edge days.

The switch to safari is likely tied to something else, given Apple's growing advertising revenue. Meaning, move away from one advertisement engine (Chrome), and move to another (Safari).