Warning: Server and client are using the same version but different platforms!
... still displays on standard output. While most players do not get to see this message, those who do do not understand what this warning means and how they may need to respond to it. So it is just unsettling to them. Developers could evenly well see this message on the game logs instead. There are also no known issues with platform compatibility.
Summing up, I think this message should no longer display on the terminal / command line output when users using a different platform than the server connect.
Alternatively, it may be a good idea to just remove the word warning (most users think that a warning is necessarily something bad, as bad as an error) and make it a simple statement (no more alarming exclamation mark which I think is there now):
Server and client are using the same version but different platforms.
This would most likely serve the same purpose while keeping debugging evenly simple for developers.