Since updating to Android Studio 4.1 I constantly get this error message on startup:
Plugin Error: Plugin "Fabric for Android Studio" is incompatible (supported only in IntelliJ IDEA).
That plugin is neither listed in Settings > Plugins nor is it not contained in the expected path.
After downloading "Fabric for Android Studio", it turned out that it is called CrashlyticsPlugin.
And when searching for CrashlyticsPlugin it turned out, that the JetBrains Toolbox uses different paths than the standalone installer does. Removing all occurrences of the CrashlyticsPlugin from %USERPROFILE%\AppData\Local\JetBrains\Toolbox\apps\AndroidStudio\ ch-0 and ch-1 solved the issue.