What’s this?

[Jdeal1]

What are these discoloration marks that look like drywall nails?

 

[billshack]

yes looks like it.

 

[Jdeal1]

What makes that gappen

 

[bud16415]

Nails or screws and then drywall compound to fill the indent before painting. The paint attaches to the compound differently than the drywall and or may absorb deeper or later absorb moisture differently depending on the primer and paint used.