broken GTK design all of the sudden

[fabiscafe]

for some reason the UI changed to some dated, ugly looking design, that clearly is not Adwaita anymore, wich is my default GTK design. I've not changed a thing on my system when it comes to style changes. I cant find any setting for this. It's quite hard to deal with this app now on my touch device as well.

I'm using the flatpak from flathub.

[fabiscafe]

When I use

GTK_THEME=Adwaita com.github.muriloventuroso.easyssh

it will launch with the correct design again (while some elements are bigger than before). Looks like there is something broken in there. However easyssh seems to be the only (flathub+gtk)app with this issue.