Unlike Sabrina and Chloe, both Felix and Nathalie have yet to actually apologize, or take any accountability in Felix's case, for their actions
Sabrina can go for the most part without saying thanks to Daddy cop being a relatively recent episode, but to sum it up, not only did she express clear and genuine remorse and shame for her past actions she actually apologized and took accountability for them unlike Nathalie and Felix.
Then there's Chloe, who has apologized and taken more accountability then Nathalie and Felix combined! She apologized to the heroes during Queen Wasp, express genuine guilt for getting her father akumatized in Malediktator, joined Ladybug in making up for that, and not only apologize to both Ladybug and Bustier in Zombizou but made up for her actions from that same episode by sacrificing herself for Ladybug and giving Bustier a gift in private.
As for Felix and Nathalie...
Felix hasn't apologized or even try to make up for trying to SA Ladybug during his debut, intentionally preventing the heroes from defeating the villains of the day in order to attempt to strike a deal with Hawkmoth, stealing all of the miraculous, willingly giving Gabriel back Adrien's amok/slave-coller alongside said miraculous he stole, murdering the sentimonster he made in Representation, or when he committed an actually fucken GENOCIDE against humanity, an act he took JOY IN DOING.
Hell given how he didn't bother to help out during Re-creation it's clear he has yet to take accountability for being the one directly responsible for Gabriel becoming Monarch in the first place either. Even his 'good' moment in Representation means nothing as he only hints at Gabriel being monarch because Gabriel & Tomoe are interferes with the romance he's trying to start up with Kagami, and for the most part completely comes across as him trying to justify stealing the miraculous from Marinette.
Nathalie meanwhile has yet to apologize for willingly working for Gabriel since the beginning of his reign of tyranny, or more importantly, apologize or express any form of guilt from WILLINGLY MURDERING A CHILD. That's not even mentioning how instead of going to the heroes or police and exposing Gabriel after suddenly caring about honoring Emile's last wish to her, she willingly remained silent about Gabriel being Monarch and still occasionally aid him in his goals.
Hell even her one moment in the finale where she did finally do something good is potentially undercut alongside her 'redemption' thanks to El Toro de Piedra's post credit scene making it so we don't even know if she's really even on the goodside now or if what she did in the finale was really about her making up for her inaction from that entire season.