In my opinion, that sort of finish is typical of very low grade mild steel (MS), where the swarf is tearing and periodically reattaching itself to the workpiece.
Someone gave me some old lift (elevator) 3″ diameter winding axles, removed from a city office block in Melbourne. I was delighted until I came to use it. It turned out to be rubbish, and wouldn’t turn or mill without wearing out cutters.
With reference to this thread, a test with the same cutters on some free-cutting MS might prove me wrong. And of course, having the cutter height set correctly if that wasn’t already checked.
A decent cutting fluid might also yield more information.
Regards,
Sam