The 25-year-old had another night to forget at Anfield on Wednesday night as he saw his second half penalty saved by Caoimhin Kelleher when presented with a chance to draw Real Madrid level.
Mbappe was largely ineffective throughout the 2-0 defeat despite the absence of Vinicius Junior which allowed the Frenchman to occupy his favoured left-sided position.
Tasked with being Madrid's talisman at Anfield, Mbappe failed to live up to expectations to the annoyance of ex-Arsenal and Chelsea star Petit.
The 1998 World Cup-winning midfielder claims that Mbappe is not displaying his usual confidence on the pitch, something many expected after he finally landed his dream move to Madrid.
"You can see it in his eyes, he's lost," Petit told French outlet RMC After Foot." Kylian Mbappe is not happy. It's completely paradoxical because he always wanted to go to Real and have all this attention."
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Mbappe's time in Madrid has been clouded by reports of dressing room unrest among the club's star names.
Despite leaving France this summer, Mbappe continues to make headlines in his home country following his acrimonious exit from Paris Saint-Germain and his omission from Didier Deschamps' France squad for the last two international breaks.
The decision to appoint Mbappe as France captain continues to divide opinion more so after his loss of form stemming from Euro 2024.
Mbappe remains locked in a legal case with PSG to recoup £45million in wages after the French champions withheld payments to him during the end of his time at the club.
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He had previously gone public on his intention to waive a loyalty bonus owed to him as a means of subsidising PSG ahead of his free-transfer switch to the Santiago Bernabeu.
The France star later U-turned on his decision to financially support his hometown club leading to a bitter ongoing dispute.
A recent poll run by Le Parisien showed that Mbappe's popularity has plummeted in France over the past 12 months, partly due to his conduct and individuality on the pitch and Petit believes his actions are now coming home to roost.
"Karma. I believe a lot in karma," Petit added. "When you do things that irritate people, you start to have all these people against you.
"Everyone in unison wants you to get your act together."
Petit's broadcast partner - the often outspoken Daniel Riolo - also provided a scathing assessment of the forward.
"He breathes discomfort," said Riolo. "It's sad but [Mbappe] is no longer a football player. He does nothing, achieves nothing. He can't even run anymore."
The panel went on to criticise Carlo Ancelotti's handling of Mbappe, saying the Italian's claims that everything is fine with Mbappe is wide of the mark.
"Everything is fine, no problem," one of the panel said, calling it an objective lie to those witnessing a player who has struggled for form for some time.
"I have seen players go through rough patches, but in his case, it looks like the curtain has fallen. There is nothing left. That's it," the panel concluded.
"Now we are witnessing Mbappé's failures. He should acknowledge it and talk about it. He can do it. He should say something. For years, we've seen him as a Robocop.
"Visibly, the robot is no longer there, he is disconnected. So if something isn't right, something is dragging him down."
Despite a difficult start to life in Madrid, Mbappe's stats of seven goals in 12 La Liga games makes for adequate reading.
Mbappe finds himself one goal adrift of Vini Jr's eight, but has the opportunity to fire Madrid back into form in the Brazilian's absence through injury.
France legend Emmanuel Petit delivers harsh truth about Kylian Mbappe's leadership
Following the defeat at Anfield, former Real star Gareth Bale reserved the highest of praise for the World Cup winner
"He is the best in the world and it's just a matter of time until he demonstrates that," the Welshman told TNT Sports.
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"[Mohamed] Salah and he both missed penalties, but with Liverpool winning, only Mbappe's miss will be discussed."
Mbappe can quickly put the disappointment of Wednesday night behind him when Ancelotti's men host Getafe on Sunday.