This is a custom music mod who is "Dystopian Devastation" from the menu music of Killing Floor Springs 2021 update (and also this music forced me to play KF2)

Preview video: https://youtu.be/9cZCyXJwWgQ

To install it, you need Bearlib, download the mod, excact to mod assets -> mod_overrides (Make yourself the folder if needed).

(This mod add one extra music to select to your track list before go to the map, during the planification)