A Comparative Review of iOS Browsers

"but users care more about the browser features" Underlying engine affect features.

This for example.

"Bugs Chrome, Edge, Brave, Firefox – all of them use mobile WebKit on iOS. But for some reason, they still occasionally show bugs and visual glitches that aren’t present in Safari. The two I see most often: horizontal jiggle while scrolling and sudden left-right margins added if I switch back-and-forth from the browser."

Why it's only happen to other browsers? Can these dev fix it when they don't have access to underlying engine source?

iCab is missing.