What am I missing on iOS safari + content blocker compared to firefox + ubo then? I used ubo on chrome on the desktop, but not a chrome user anymore. Honestly don’t see the difference compared to macos + kablock (and hush).
It's not surprising you wouldn't see much difference between Kablock/Safari on desktop and content blockers/Safari on mobile - I believe they're basically the same kind of interface for providing blocking rules.
FF's extension interface allows more sophisticated rules & blocking behavior, and uBO takes advantage of that. You may be fortunate that you don't happen to spend time on sites where it makes a difference, but I'll say from experience that I do see ads and annoyances on some sites on my iPad that I do not see on my laptop or Android phone (both running FF with uBO). It's not a huge difference - as was said above, Safari with content blockers is certainly usable, but uBO is still better.
I am speculating a bit here because I haven't dug too deeply to confirm this, but I think one technique sites use to work around ad blockers that Apple-platform content blockers don't handle well but uBO does is serving ad content from the same origin as real content (and even with similar paths as real assets). Last I looked, Safari content blockers were mostly limited to old-style rules of "block assets matching this URL" and "block this css selector on this site", so when sites do the work to make ad assets look the same as real content assets, that can't be blocked as effectively with content blockers. uBO can inspect the DOM and other aspects of the page content blockers can't, so it can do more to detect those techniques and block them.
It's not as bad as no adblocking altogether, but very far from firefox with ubo on Android.
It's good enough to use however, and android has it's own issues.