Odd metal on rear diff plug - concerning?

It is normal.
Nothing to worry about.
It’s left of debris from machining the housing.

 

Maybe left over of a bolt hole drill.

 

Agreed. It's left over from the manufacturer and not uncommon.

 

I found a very similar piece of metal on my first diff fluid change, and other members shared photos and anecdotes of the same.

 

I saw a mild brass in the oil pan of the deferential and the transfer case- hope it isnt bad

 

I wouldn’t worry about.
I seen some metallic coloration in my diff fluid the first time I changed it.
No problems yet.

I think you’ll be just fine