Dark theme is used on clean start despite "Light (Arduino)" being the default

[AlbyIanna]

When the Arduino IDE is started from a clean system (no configuration files from a previous IDE run), it is using the dark theme even though the default preference setting is for the light theme.

Steps to reproduce

1. Delete the IDE's configuration folders (e.g., C:\Users\per\.arduinoIDE, C:\Users\per\AppData\Roaming\arduino-ide,
2. Start the IDE. Note that it is in dark mode
3. Open File > Preferences. Note that the theme is set to "Light (Arduino)".

Expected behavior

The IDE uses the "Light (Arduino)" theme by default.

Environment

Version: 2.0.0-beta.11-snapshot.da6b66f
Date: 2021-10-06T08:06:21.909Z
CLI Version: 0.19.1 alpha [718bbbf2]
OS: Windows 10

Additional information

This does not occur when the same steps are followed with 2.0.0-beta.11