I tested installing some web browers, kdenlive, yuzu and libreoffice and without knowing I ended up with 3 different runtimes and the total storage usage (with deduplication) was 4.79 GIB.
Meanwhile with 33 appimages that I have (which includes same flatpak apps I mentioned) are using 2.2 GiB.
It doesn’t matter if they share if in the end they end up using several times more storage than the appimage equivalent.