He's really not playing under lower pressure, or in a weaker team, or even in a system designed to generate him and only him chances.
He *is* playing in a somewhat weaker league better suited to him. He's also getting the best coaching of his career, by a guy who wouldn't swap him for Lewandowski, and just entered his career-prime years
Top 5 striker in the world? A stretch, depends on whether you'd count guys like Cristiano, Salah, traditional second striker types. That said, other than Lewandowski, Kane and Benzema, probably Haaland....who else is there?