Potential Nickel Error/Variety

Hello fellow collectors, I have a nickel and I’m wondering if it’s an error. Basically the nickel’s outer border is pushed in if that makes sense. I have two others with this “condition”. Just wondering if this is damage or an error. I’ve attached images of the nickel below so you can see what I mean.
0
Comments
Looks like damage and environmental damage to me.
My Original Song Written to my late wife-"Plus other original music by me"
https://youtube.com/playlist?list=PL8A11CC8CC6093D80
https://n1m.com/bobbysmith1
That’s what I thought at first but just wanted to make sure. Thank you!
@LukasA.... Welcome aboard... Definitely PMD (Post Mint Damage). Good pictures... Cheers, RickO
ROAD RAGE
BHNC #203