He isn't absolutely world class, though. He's a world class talent.
Foden had half a season where he performed at world class level, between late December 2023 and May 2024. That's about 5 months. Before that he was mostly a really good and highly promising player, but not world class. He started games on the bench when the Treble was decided.
Note that even during those 5 months of rich goalscoring form, he wasn't exactly outstanding in the other aspects of his game. Take both games vs. Madrid last season. He scored an exceptional goal at the Bernabeu and that was everything he did in over 200 minutes. At the Etihad he was poor.
He has the talent to be absolutely world class. But he needs to be a lot more consistent, not just in scoring goals, but also in creating chances. If he isn't consistent, maybe he will benefit from watching Bobb or hopefully Wirtz from the bench.