OperaGX: Difference in handling commandline arguments when executed from console vs executed as subprocess from another process

I don't know the release version of the previous OperaGX launcher (the actual exe) but I could call Launcher.exe and feed it an unquoted url to have it open a new tab in an already running OperaGX. The last update somehow messed with that as it now opens a new OperaGX window which seemingly uses a totally different profile.

So I tried getting around this by simply calling OperaGXPortable.exe from within my program.
The funny thing is, if I pass an unquoted url, it ends up in OperaGX as a link with folder of the calling program prepended, like

file:///C:/folder/of/calling/program/https:/www.somesite.com/somepath/somepage.htm (note the missing slash before the www)

I created a cmd file to echo the commandline and final argument to make sure that what was actually sent to OperaGXPortable.exe was in fact just the url which convinced me that it was OperaGXPortable.exe that somehow deduced the foldername where the calling process is located and prepended this to the passed url. Why? Beats me...

Testing this from a cmd console, calling OperaGXPortable and passing it an unquoted url leads to the correct url getting opened.
But only when doing so within an already open console window... doing the same from a called CMD file leads again to the above mention mangling

It seems that if OperaGXPortable.exe is called from within another program, it expects a url, passed as argument, to be quoted.

Ok, so next step was sending the url quoted... this then led to a totally unexpected different result, the url ending up in the addressbar now looked like

%22https//www.somesite.com/somepath/somepage.htm" (note the missing colon, the urlencoded opening doublequote and the still present trailing doublequote)

The only way I could get it to work was calling a cmd file and add the quotes in the cmd file... major annoyance is the flashing console window...

Any way to fix this?

Windows10 64bit
E:\PortableApps\OperaGXPortable
Upgraded from previous release