Narex Richter flatness

Anyone else surprised by how far off flat the backs of their Richters were? Or is it just my set?

I'm actually considering sending the whole set back.

Been using the Narex cabinetmaker set for years and found them great for the price.
Felt the need for a steeper bevel, for 'fine' work. I spent weeks researching 'premium' chisels (and searching for vintage options).

I spent an hour trying to flatten the 3/4" (with 100 grit paper on a surface plate). I don't have a feeler gauge with me but 3 out of 5 of the chisels have a significant belly to them.
Really annoyed to be honest. The money you spend on these 'premium' chisels. I feel stupid for not checking them all before going to commission them. Worried the shop won't return them.