Theme change does not work

[iGadget]

Describe the bug When changing the Theme under Preferences, the theme stays the same.

To Reproduce Steps to reproduce the behavior:

1. Go to 'Preferences -> Appearance'
2. Click on 'Theme'
3. Change Theme to a different one than currently in use
4. Theme does not change.

Expected behavior Theme should change from Light to Dark or vice-versa.

General information:

• Distribution: Pop!_OS 22.04 (light theme)
• Installation method: Flathub
• Version [e.g. 0.1.0]: 0.3.3.
• Device used [e. g. desktop, phone...]: Desktop

Additional context Apparently already known by @Diegovsky as per https://github.com/xou816/spot/issues/515#issuecomment-1118436691