Weird choices in default application menus

### What Happened?

After installing Firefox (flatpak), it didn't appear to be selected as a web browser in the dropdown. Even after a reboot, that didn't change.

Now, it's also selectable (and selected by default) for other unrelated purposes:


Sames is true for Thunderbird (flatpak). It's not selectable as default mail client or calendar.

### Steps to Reproduce

1. Install Firefox (or Thunderbird)
2. Try to assign is as a default app
3. Does not appear in the menu

### Expected Behavior

Both applications should appear in the menus.

### OS Version

8.x (Early Access)

### Session Type

Classic Session (X11, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info

```
eeeeeeeeeeeeeeeee wout@Framey
eeeeeeeeeeeeeeeeeeeeeee -----------
eeeee eeeeeeeeeeee eeeee OS: elementary OS circe 8 x86_64
eeee eeeee eee eeee Host: Laptop (12th Gen Intel Core) (A8)
eeee eeee eee eeee Kernel: Linux 6.8.0-48-generic
eee eee eee eee Uptime: 12 hours, 25 mins
eee eee eee eee Packages: 1812 (dpkg), 18 (flatpak-system), 18 (flatpak-user), 7 (sn)
ee eee eeee eeee Shell: bash 5.2.21
ee eee eeeee eeeeee Display (BOE095F): 3000x2000 @ 60 Hz in 13" [Built-in]
ee eee eeeee eeeee ee DE: Pantheon
eee eeee eeeeee eeeee eee WM: Mutter(Gala) (X11)
eee eeeeeeeeee eeeeee eee Theme: Yaru [GTK3], io.elementary.stylesheet.blueberry [GTK4]
eeeeeeeeeeeeeeeeeeeeeeee eeeee Icons: Yaru [GTK3], elementary [GTK4]
eeeeeeee eeeeeeeeeeee eeee Font: Inter (9pt) [GTK4]
eeeee eeeee Cursor: elementary
eeeeeee eeeeeee Terminal: x-terminal-emulator
eeeeeeeeeeeeeeeee CPU: 12th Gen Intel(R) Core(TM) i7-1280P (20) @ 4.80 GHz
GPU: Intel Iris Xe Graphics @ 1.45 GHz [Integrated]
Memory: 7.55 GiB / 62.51 GiB (12%)
Swap: 0 B / 3.80 GiB (0%)
Disk (/): 70.56 GiB / 910.86 GiB (8%) - ext4
Disk (/media/wout/1TB Framework): 168.41 GiB / 913.59 GiB (18%) - ex4
Local IP (wlp166s0): 192.168.1.253/24
Battery (Framewo): 85% (2 hours, 44 mins remaining) [Discharging]
Locale: en_US.UTF-8
```