Hi @kiq33. You might be interested in this information shared by a forum member:
Please note that a bug in the Arduino IDE 2.0.3 release broke support for installing additional themes (whether they are ones you downloaded from the Visual Studio Marketplace or a custom theme you made yourself). That bug has already been fixed, so make sure to update to the latest nightly build if you decide to install additional themes. The nightly build download links are listed here: