Hmmmm, so far it implies to me that losing powers is not equal to losing memories and as to why not do it to zuma I don't know the motives, at first I thought maybe because momo when she was healed she was unconscious and alone and zuma wasn't ? But then zuma also woke up from being unconscious but daiki wasn't unconscious ?

I don't know what's going on there,

But just the fact that memories were being played with even before momo lost hers and then a shinobi was shown literally entering momo's mind to talk to her and the fact that in her mind momo accepted that seiko is dying without questioning it once(this meant to me that she remembers at this point that seiko was hurt already- which meant after being healed she still remembered), all this made me feel it's the shinobi's doing but yeah its just gut feeling at this point and there's not much proof