MrMeTheFirst Its more a struggle in technique than an actual change lol cause she’s still trying to stroke him as thlugh hes still got a foreskin but the tight and dry skin means that shes struggling to get a proper stroke on his cock without stretching his skin to far and hurting him, so partway through she has to loosen or simply entirely remove her grip from his cock entirely. This is what no foreskin does to a cock as no gliding continuous and continuous action.
