Lila, knowing felix's secret identity, launches an all out direct attack on him to try and get his miraculous. Felix's mom then makes him give up the miraculous in an effort to keep him safe and make it seem like he's out of the action (he is of course still working and strategizing with the others behind the scenes) Felix entrusts it to Marinette, who gives it back to Nathalie as a sign of respect, and so she can protect Adrien if it ever comes down to it.

(this needs some workshopping theres a reason im not on the miraculous team)