It's just a color filter, you might even be able to do it in camera without external software depending on what they're using.

They probably set it to that exact shade of red with almost no tolerance on either side of it to get minimal crowd color.

If there was a way to just get b/w output (I’d assume there would be), then yes, a red lens filter should do the trick.

Clearly but it hasn't been done yet on AEW television so I was very happy to see that they found a working option for it.