Flathub build of Firefox 82.0 on CentOS 7.8 does not detect native host connector

I have a similar issue to https://gitlab.gnome.org/GNOME/chrome-gnome-shell/-/issues/26 but on CentOS 7.8 with GNOME 3.28.2.

Have chrome-gnome-shell.x86_64 10.1-4.el7 @base installed, and within Chrome 86.0.4240.111 (Official Build) (64-bit), extensions.gnome.org works just fine.

However, over on a Flatpak of Firefox 82.0, I inevitably see Although GNOME Shell integration extension is running, native host connector is not detected. Refer documentation for instructions about installing connector.

I had previously had the snap build of Firefox installed, but saw the warning from the developer not to use the snap version, so I uninstalled the snap version and installed the Flatpak version, but alas, the Flatpak version still gives the same error.

Please advise.