"This product does not use the domain you selected for Instagram Shopping"

Same here. I purchased my own domain so I could have more control over my website and now like you, Instagram is saying my catalog doesn’t match how I originally set up Instagram shopping. And I don’t have the option of changing that domain anywhere. All of my items are the same and everything and everything syncs perfectly on Facebook from my site. It is just my domain that changed. I have contacted Instagram and Facebook support. I’m waiting to hear back.