While I love good news for Linux gaming, this article is IMO a litre too positive. In the last part, notebookcheck picks the games that Linux distros were best in and presents a biased picture.
But the general message is positive: When games run under Linux, the performance is probably equal or better than with Windows. (And Windows has compatibility problems too).
Yap, ProtonDB give us a good picture, mostly games still have minor issues. But, I like this kind of thing because show potential. If gamedev do they homework, the Linux experience could be better performance.