This is a glitch WGT are aware of and which they're planning to put right on the next downtime (allegedly).
The issue has been raised a lot on the Discord forum and apparently the only way to see/delete these invitations is to leave your current CC and rejoin it if you don't want to accept the invite (which if it's cold calling is pretty likely....a Club/player would normally ask you first before just sending an invite...).
Hopefully sorted soon but probably best to ignore the purple dot for the moment unless you're expecting an invite.