Wow, haven’t seen that one before. I have a friend who flies a ton and with a Minari 200cc and most of his flying buddies also fly them now. From his experience the Minari to be more reliable than the vittorazi mosters that he has been flying for years. So maybe I’ll ask him if he has ever seen anything like this.
One more thing. I am not super familiar with the Minari engine, but entirely based off the deep blue coloring in the exhaust, the engine could be running very lean. As you may know 2 stroke exhaust gasses tends to be at nearly half the temperature of 4 stroke exhaust gasses. For this reason I have never seen a 2 stroke change the color of the pipe like that and it is a possible indicator that it is running very lean and very hot.