The old tradition is to have the most recent standard C version being the default in POCC. Right now you get C2X which is unfinished/experimental, so perhaps a bit questionable. The C2X standard is supposed to be finished in 2023 (we'll see about that). Whenever it's finished it will get a proper date. Right now all I have is a fake date. Any date. You can always use the /std option to choose something better than the C2X standard.