GTK theme is not applied if the app is run with flatpak
I installed the app from flathub's flatpak and it's working fine, except for GTK theme (Arc in my case) not being applied. Of course it's installed as a flatpak itself, and it's working for other flatpak apps, both on 3.24 and 3.26 runtimes (even some master/3.27 ones), so I think the problem is not in my config.