Depending on the quality of the brand I would respond truthfully and based upon facts from reviews and personal use.
Stating that all screen protectors reduce sensitivity is a false blanket statement. I'm simply asking you to prove to us that you've actually used a quality brand and felt it reduced sensitivity. I've tested over a dozen myself for reviews so I actually know quite a bit about each brand.
Which one do you recommend? I am more than happy to try one if it doesn't reduce anything.