I don’t see any signs of repair, but I can see where there’s a label which has been removed and the local shop’s label affixed. That’s why I thought maybe it happened with the changing of the label.
I’ve had one luthier say that it probably happened during the build and it wasn’t a big deal.
@EddieC . I enlarged the provided photo and managed to see a small splinter in the component you call a liner. That feature provides additional glue contact area during the assembly of the back plate to the ribs. It looks like the remaining portion is adequate to fulfill the intended function.
If you are not experiencing any buzz from the splinter fragments, they should not create much of a concern. Glueing them back in place would likely require back removal.
Success is the progressive realisation of a worthy ideal. —Earl Nightingale.