If the employer makes a correction to my W-2, do they have to indicate on the form that it has been amended in some way?

Hi, my name is Mary.
I'm just about to wrap up my 2021 taxes, but I want to wait until I hear from the community.

I'm concerned. I don't want to get a past employer in trouble, but when I was inputting the data from the W-2 I got into Turbo Tax, there was an error message saying we needed to get a corrected W-2, that we had overpaid on Medicare by only about 8 dollars. We let our employer know and she quickly got us a W-2 with the corrected amount.

My concern, first, is that the new W-2 doesn't have a box checked that says it was amended. There's nothing on the bottom of the form that indicates it is for a corrected W-2, either. Is this acceptable since I hadn't filed my taxes yet? I don't know how to answer the question on Turbo Tax that asks if I have a corrected or amended W-2.
While the Medicare number changed, I noticed the tax and annual wages and everything else stayed the same. We haven't received a refund from the employer yet. I'm really not worried about it because it was only $8, and it might be on its way through the mail as I write this. I just don't know how these things work. I don't want to file my taxes and possibly get my employer in trouble. Please advise. My other concern is that for over 9k in wages, it looks like only $18 in federal taxes was taken out. Is that right? That number just seems rather low to me.

Also is there a good way to connect with a tax person for free advice over email?
Thank you in advance for the help!