Not asking for legal advice, just educated intuition.
Lets say a programmer creates a program to provide a service, for instance (hypothetically) face recognition. User logs in, uploads pictures and the program informs their friends that a picture of them was uploaded (or whatever).
Now the programmer finds another GPL software that can greatly enhance the performance of their program by preforming some initial CV analysis. Can the programmer place the GPL software on a private RPC server and have their paid software communicate with that server?
Meaning would that require making the new program GPL aslo?