HELP. PLEASE. (color change)

[Opuntia]

Please can anyone tell me does this looks like hatching failure syndrome? I have only just noticed the colour change at the top of the large 3rd section from the head it was black. The baby is two week off 1yr and weighs 47g, only gained 1g in the last 4 wks despite eating well.
Thanks for any help given.

 

[Yvonne G]

No, I think that's just from rubbing his shell on the ground as he walks.

 

[Opuntia]

Thank you.
Hubby said it looked like rubbing, not sure how. Do I need to find what is caused it? Is it permanent shell damage?

 

[Sarah2020]

You need to watch where it walks to see the cause of the shell rubbing. Have you stones in the enclosure or a ridge?

 

[Tom]

This little squiggly lines are harmless and normal. I don't see anything wrong with this plastron. Certainly no indication of "Breeder Failure Syndrome" in the pics.