Around 2014, there was a page on BianchiUSA.com, about steerer damage from incorrectly installed stems. It appears to be gone from the internet, but a couple of the images are in this old post I did:
https://www.bikeforums.net/21006763-post22.html
There's a "not damaged" photo, and a "steerer tube damaged" one, and an extremely crushed image, too.
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Steerers are quite strong. Even the short, cutoff end after I shortened my steerer was sturdy.
I wouldn't worry about surface damage, but I'd be concerned about crushing extending farther into the layers, especially if it's been ridden at lot over rough surfaces with an incorrectly tightened stem. I could expect the damage to get worse over time.
Those green arrow scrapes seem to be on the surface?