Well, dug out my P01 Omega box. It's the center of the left side decocker shaft. How in the world did that break off?
Mine looks like it's a machined part of the shaft. May not be, but it looks like it is.
Yours looks like it's a separate piece that is made, then pressed onto the shaft. Darn silly/cheap/fragile way to make that piece, in my opinion. If that's how they do it. That metal "ring" that slides down around the shaft is very, very thin and if really made that way it's a definite failure point for the decocker set up.
Really surprises me if they did it that way.
But if, on the other hand, its machined as part of the shaft, how in the world did it break off like that??? Don't see how it could.
Edited to add - Yup, put on a second pair of glasses (my mode for working on small parts) and got a bright light and it does appear that is a two piece assembly. I can see the indention between the part that broke (on yours) and the shoulder on the decocker shaft, as well as the ring creating a hollow spot on the left side where it was pushed on past the round portion of the shaft (leaves sort of a half moon shaped cavity on the left side.
Sounds like your pistol would still fire?? But if you can't decock it with the levers it's like carrying a safet model cocked and "not locked."