From the picture, it's the end of trigger bar. Because this piece is stamped, seems like the stamping cause too much stress and part of it cracked. I have experience two of these myself but the trigger bar usually does not jump that far forward, and trigger bar don't crack until way past 10K rounds.
Depending on where you are, all it needs is a new trigger bar (and perhaps a new trigger bar spring, if it's mangled). It should be a pretty easy fix. We have parts in store to fix this issue but since it's relatively new, I would call SIG to sent a call tag so you don't have pay the shipping charge.
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