They sent the same drawing we approved, with a circle around the flange. The extra projection beside it is exactly what I'm asking about.

We had a quoted adapter turn into whatever was available in packing. Don't let the circle settle it. Send a clear side view and ask them to identify the projection against the supplied drawing, or admit that drawing doesn't describe it.

I've sent that side view with the projection marked and our bracket shown beside it. Also stated that moving our bracket is not an accepted change, which apparently needed saying.

Who will assess the whole assembly if they finally propose a different drawing?

Our tool designer. She has the accepted arrangement and delivered photos, but says she needs their actual assembly identity and data before assessing an alternative. Purchasing is keeping that separate from the original order commitment.

Has the seller acknowledged the visible difference at least? Three days of arguing about a drawing they already sent you won't get your designer the missing information.