Flatpak app window icon on Wayland

[Damglador]

Steps to Reproduce

Steps to reproduce the behavior:

1. Install the app as a flatpak
2. Enter a Wayland session (KDE Plasma in my case)
3. Launch Discover Overlay Configure
4. See error

Expected behavior

Discover Overlay Configure should have it's icon in the bottom panel and Alt+Tab menu

Problematic behavior

It has Wayland icon

Desktop (please complete the following information):

• Operating System / Distribution: Arch Linux
• Desktop Environment: KDE Plasma 6.2.5

Installation Method

• flatpak

Discord client information

• Install method: Arch repos
• Version: 357831

Additional context

On Wayland for an app to have an icon it's WMClass name should match with the name of a .desktop file which specifies the icon. Basically if we have io.github.trigg.discover_overlay.desktop, the WMClass name should be io.github.trigg.discover_overlay, right now it is discover-overlay.