Do you recognise this broken part?

2019 YZ250F. 

Starts fine. 
Runs fine. 
Sounds fine. 
Changes gear fine. 
Everything about it is normal. 

This part was found on the oil strainer this morning. 

Absolutely not something dropped in the engine during maintenance- I rebuilt this thing top to bottom 88hrs ago. It hadn’t missed a beat and has had countless oil changes in the last 87hrs. 

I’ll be stripping it out on Monday morning. 
My first thoughts are it’s some kind of ‘tab’ broken from the gear change shaft. 

It’s made of steel.