I tried that too, but there has to be a way, to link workouts to a specific icon/image without an app. The Matrix Bike training was created by using the connect to gym equipment feature that apple offers. I have no Matrix app installed from where the icon could have come from

I thought about this too, but f.e. the Matrix Workout was created by connect the gym equipment to the Apple Watch. So in the case above, I installed no external app, but only connected my Watch to the Bike. So the Icon has to come from somewhere else, since I don't have a Matrix app installed.

Since I was indeed not on Beta 3, I will check this solution once I get the chance, and will update the ticket accordingly.