Looking up the iTunes User Guide, it defines "Explicit" as
A label—issued by media producers—that alerts consumers to content that might be inappropriate for children.
So, it appears that they are going off the RIAA's definition of "Clean/Explicit"
Additionally, I was able to find a iTunes Users Guide for PC that goes into more detail:
There are a few ways that you do to achieve your requirements.
But you have to disable Apple’s SIP which I don't recommend personally.
So, I would suggest you use this third-party application named as Mac Media Key Forwarder. Use the latest version 3.0 for Catalina.
You can prioritize which app you would like to control or you can go
with the ...