I believe all Flatpaks incorporate the codecs already.
Flathub even has hardware decoding with the drivers they distribute. However, Flatpak applications need to specifically opt in to ffmpeg-full rather than the normal ffmpeg package, which has support for patent-encumbered codecs.
Fedora Flatpaks, on the other hand, have no such codec support.
Fedora is a top-tier project and I completely understand why they weren’t comfortable risking patent law unnecessarily.