no, I haven't done the clutch disc replacement because after I had a oil change the problem was gone. During my last maintenance activity I found another thing:

The X5 is very sensitive for the positioning of the rear wheel. In the past I had just checked the position marking at the swing arm to adjust the rear wheel and chain.
Then a unusual chain rattling sound came up on my good DID chain.
At last maintenance time I saw that the chain was not straight between front and rear sprocket. So I used a laser pointer along the chain to get a straight positioning and measured the left and right distance from rim to outer swing arm edge.
I found the rim before correction was out of center about 8mm to the left.
Now with the rim and chain adjustment the sound is gone.

One question to the experts here:
When putting up the bike on a stand so that the rear wheel can turn freely without load and then run the engine in gear 1, the chain starts jumping on the way from rear to front sprocket and want to jump over the small sprocket. Is that normal?