Mine started doing this recently as well. I pulled the clutch cover and about a quart of oil came out. That's almost a quart too much!
I checked the oil jet and sure enough,it was very loose. Like, out of it's threaded boss. Tightening it fixed the problem.
Long time T6 user here.
Maybe check that before getting carried away bleeding and changing oil brands...?
2012 KTM 990 Adventure