The lack of borders on some apps can make for a visually confusing experience. Pre-installed GNOME apps seem to have shadow effect that defines the border a bit. But some stuff from from Flathub, I think they’re qt apps, are borderless. Is there an extension or other fix for this?
On the attached screenshot, you can see how the borderless windows bleed into one another. KeepassXC was downloaded from Flathub, uses QT and Wayland.
I’m inclined think it’s a Keepass thing and not necessarily a Qt problem - Flameshot is also Qt but its pop-ups look normal with Adw-gtk3 theme and other themes 
I don’t use Keepass but I do know Gnome has its own Keepass-compatible password manager, Secrets. Maybe it’s worth looking into?
It’s my understanding that KeepassXC tries to keep a consistent look across Linux, Mac, and Windows. I’ve used it on all 3, and that is a nice aspect. So that could be a factor with the borders.
I did check out Secrets and liked the design. It fits in with the GNOME way of doing things very well. It’s not feature-complete like KeePassXC but maybe that will improve with time. Unfortunately it crashed 3 times within 2 hours of use. Not great, and I certainly wouldn’t use something unstable with my real passwords file. I wouldn’t want it to corrupt the database.
I do hope that Secrets catches up in terms of features and stability, but it’s not there yet.
