User blog comment:Katachino/deku’s marking/@comment-25044056-20181215160151

My best guess is that Hitoshi Shinso is descended from the original OfA user, which would could be the reason why OfA resonates in Deku when he's near Shinso but not when he's near Tomura Shigaraki (Shigaraki is the grandson of the 7th user). Perhaps this also has something to do with All for One "hearing the voice of his little brother".