That had been harmonized with C++ in C23 (e.g. func() is equivalent with func(void) now).
It's not really relevant for main() though, even in older C versions main() works fine and simply means "I don't need argc and argv".
This is about a function definition, not a random function declarator. C23 does not change anything in that case.
This is about a function definition, not a random function declarator. C23 does not change anything in that case.