Found this in the oil...

[stiubhartach]

I've never done a rod bearing change on a BMW before, but this link has some good info. The front drive train will mean more work, but it looks doable. You remove the oil pan and running gear.

An experienced mechanic should be able to tell if it's a bearing by listening to it run. That should be your first step. And much cheaper than getting in there and finding that's not the bearing after all.

The flecks are brittle, so they could be carbon from a lower cylinder wall chipping off.

An oil test will also tell you if the bearing has come apart.

https://www.turnermotorsport.com/c-392-rod-bearing-kits