I am married to an intact man, so I know how things work. If you've lost the most sensitive and pleasure-giving part of the penis, that's obviously going to reduce pleasure. You can't test the sensation of the foreskin on a man who doesn't have one, obviously: That would be like me cutting off my pinky and then insisting my pinky was still able to feel as much sensation as a person with all their fingers.

I don't want to argue, but I offer these:

https://blogs.bmj.com/medical-ethics/2016/04/22/circumcision-and-sexual-function-bad-science-reporting-misleads-parents/

https://pubmed.ncbi.nlm.nih.gov/23374102/

https://circumcision.org/men-circumcised-as-adults/