This is a patch with an AAS file by Dark PnP 2005 which allows you to add bots to the match on the basic official map TEST_BIGBOX, originally used only for testing purposes. I do have the patch on my PC, but I cannot find it on the Internet.

As far as I remember, I first saw it in 2021 on some .de Quake 3 dedicated German website. I think they also had a few multiplayer servers running.