IMO it was not fair. Messi didn't played well in his present club compared to the performance of Ronaldo in at El Nasir. I believe he actually won the Ballon d'Or because of the world cup he won and he had performed and manage his countries team to win.
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Just win a world cup and you win the Ballon d'Or
Ronaldo is far away from taking the Ballon d'Or for many reasons, Ronaldo didn't have any won trophies this season compared to Messi or even Haaland.
Beside that, we can't compare the level of Saudi Arabia League and Europ leagues. By the history of Ballon d'Or winners we can see that they always favorite players with more trophies and each one has a value. World cup is the most valuable trophy even compared to UCL trophy.
For me, Messi really deserve his eighth Ballon d'Or, as he is the favorite competitor to win. I believe also in the next versions we will see a competition between Halaand and Mbappé.