For several months at least I haven’t been able to paste http/https addresses into a Joplin note with the default iOS editor. Hitting the “paste” popover just does nothing. If I go back and copy the url except don’t include the “h” of http, I can then paste that string into joplin, and manually add the “h” back to make a proper URL.
Joplin on iOS/Android uses CodeMirror 6 as its markdown editor.
This seems to be a bug in CodeMirror 6 — I can reproduce this in the editor on their website by trying to paste a link copied using the "link" button on this forum.
This only seems to happen with some http/https links though. So far, links copied from the address bar in Safari seem to work.