It may be related to the webkit package and the initial login screen displayed as a webpage. I experienced it on some Linux distributions. You can try to build Projucer in so called GPL mode. In JUCE\extras\Projucer\JuceLibraryCode\AppConfig.h edit this line and build Projucer again (the login screen will not be displayed then):
#define JUCER_ENABLE_GPL_MODE 1
Or you can download JUCE 6 from GitHub, in the version 6 this login screen was changed if I remember correctly.
Thanks @MBO, it seems you nailed it, re-compiling with GPL MODE 1 fixed the issue
I haven’t tried v6 as I’m new to Juce and prefer to start with a stable release. Will keep that in mind though for further tests.