As I (and alacat) told before using osu! as source is valid ONLY for osu! theme songs or contests.You are the only one i have ever seen to state that since afaik "You don't have to" does not mean "You can't" nor does "It applies to" mean anything close to "It's ONLY valid"
I think "osu!" should be Tags same as this ( p/6065688 )
imo yes, being a featured artist doesn't mean they automatically make all songs exclusively for osuPlease move "osu!" to Tags and send me forum PM for re-qualify.
so it shouldn't be in the source I think
"osu! featured artist" can be in tags instead
when the song is for osu! official contest (MBC, Aspire), osu! theme song, its compulsory to use osu! as sourceWhen you're ready for re-qualify, let me know~
when the song is featured on the webpage, its up to the creator to choose whether to put osu! as source