Building stop, 3/4 or 1/2 inch?

Hello, quick question about my house:

A few years ago it was built and in the basement stopplugs were put into 2 water pipes.
Now I finally wanted to install a utility sink in the basement and replace the stopplug with a faucet.

It will be a dumb question, but... Is the pipe now 1/2 or 3/4 inch?
I assume 3/4, but I'm not sure.
With a caliper, the stopplug has an internal dimension (front) of about 22mm and an external of 31mm (I don't have the exact measurements in my head anymore).
I assume 1/2 inch. Not 3/4. Correct?

Does anyone know?

A photo with the recorded measured numbers would help to answer. And whether you mean thick-walled pipe or thin-walled precision pipe.

PS, packing for fittings usually have 1/2".
But they are also available in other sizes.

Right, two photos attached. That was a quick shot last night because I wanted to get ahead :/

1/2" and now I still have to reach the minimum word count for answers ;)

Thank you for the quick support!