ionic build --prod -- -- --base-href /MyApp/ : why does my environment require extra, extra -- to build properly?

Why does my Visual Studio Code environment require an extra extra -- to get the base-href parameter to work for the ionic build command?

This unusual ionic build command works on my PC ...:
ionic build --prod -- -- --base-href /MyApp/

... it runs ...
> ng.cmd run app:build:production --base-href /MyApp/

If I run the normal build command ...:
ionic build --prod -- --base-href /MyApp/

... it is missing the --base-href parmeter...
> ng.cmd run app:build:production

My colleague's PC runs the normal build command and it works as usual ...:
ionic build --prod -- --base-href /MyApp/

... it runs ...
> ng.cmd run app:build:production --base-href /MyApp/

Possible Hint: our command line's syntax highlighting looks different too: My ionic build command changes "--prod -- -- --base-href" to dark grey. My colleague's only changes the extra "--" before --base-href to dark grey.

We have the same ionic versions installed:
> ionic info

Ionic:

Ionic CLI : 5.4.16 (C:\Users\MyUser\AppData\Roaming\npm\node_modules\ionic)
Ionic Framework : @ionic/angular 5.2.2
@angular-devkit/build-angular : 0.901.9
@angular-devkit/schematics : 9.1.9
@angular/cli : 9.1.9
@ionic/angular-toolkit : 2.3.3

Utility:

cordova-res : not installed
native-run : not installed

System:

NodeJS : v14.15.0 (C:\Program Files\nodejs\node.exe)
npm : 6.14.8
OS : Windows 10

Start by reproducing both ionic build command forms on the reported Windows and tool versions, then trace how the ionic build entry point forwards arguments to ng.cmd. Done means identifying why the extra separator is required in one environment and documenting or fixing consistent argument forwarding.

Written by the indexing model from the issue text.