Unpopular opinion but for me on the night Mbappe and Martinez were better and more deserving candidates for that POTM award.
It is not sealed and it shouldn't be sealed IMO. Giving the Ballon based on 7 games of football is stupid to begin with, especially because the next Ballon will be awarded in 11 months France Football fucked up badly, they should have given the 2022 Ballon a little later to include the biggest competition of 2022, the WC. Then Leo would probably beat Benzema.
In any case, if PSG wins the CL, then it would be a toss up between Leo and Mbappe. Considering Mbappe teared the WC and would most likely be PSG's #1 option in a potential CL win, I could very well see him win the Ballon. In general I don't see the 35-36 y.o. Messi consistently outperforming Mbappe.
If another team wins the CL and Messi underperforms in the CL then it is anyone's guess.
At the end of the day, I sincerely doubt that Leo cares about the Ballon at the moment. He already has inarguably the greatest trophy cabinet in history. And no one is reaching his mythical Ballon record anyway.