Firefox profiles suck. Their UX is so bad. Containers are better but still have their issues. I use Containerise plus Cookie AutoDelete plus Temporary Containers to give me what is effectively per-tab private browsing. The major downside is that I have to copy containers.json (which enumerates all of the dedicated containers I have defined, e.g., for Facebook), my Containerise rules (which automatically puts certain web sites into specific containers), and my Cookie AutoDelete config (which says which cookies to delete and when) among browsers manually. I wish more things supported Firefox's sync feature. I ended up adding them to my dotfiles, so it isn't too painful, but it definitely isn't grandparent friendly.