this could mean three things, going in least to most interesting: 1, retcon. boring, sad, whatever. 2, sonya lied about rodion not having the mark. sure, we really dont know enough about sonya to say much about that. but i wouldnt read him that way. 3, rodion, at some point after the confrontation with sonya, developed the mark. uuuuuuuu now were getting somewhere baby
just to clarify, i dont think its like categorically impossible fur sonya to lie its just that he would have had literilly zero motivation to lie about that. he says it himself, none of the sinners know what the fuck hes talking about. he wouldnt have a reason to lie there because its meaningless to them anyway.