Bookmarks not being synced from macOS to iOS
Found a solution in case anyone is interested:

On icloud.com on "Preferences" under "Advanced" there's a link to "Restore Bookmarks", after permanently deleting every bookmark on there, I got iOS and macOS Safaris to be in sync again.

Note that even after solving the issue, iOS is taking longer than ever to sync Safari Bookmarks, it used to be almost instant and now takes more than 5 minutes.