User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0

Steps to reproduce:

elementary OS Odin 6.0 (final) set to Dark Mode
Install Firefox via Flatpak on elementary OS Odin 6.0 (final).

Actual results:

Window widgets default to Flatpak GTK defaults and do not use the elementaryOS theme (with Dark Mode selected)

Expected results:

Flatpak Firefox should use the native OS theme (in Dark Mode)

The Bugbug bot thinks this bug should belong to the 'Firefox::Theme' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Thanks Nemo for opening this enhancement. I will set this as New to get the dev team involved.

Thanks for your input.

Clara

Sounds like this is covered by https://bugzilla.mozilla.org/show_bug.cgi?id=1734073

This should be fixed by the bug 1734073. If the used theme is also installed in flatpak it works fine now.
I've got installed org.gtk.Gtk3theme.Adwaita-dark and org.gtk.Gtk3theme.Breeze-Dark from flathub to testing it.