So it's better to get a refund?
Did it specifically state Intel AX200 in your order sheet, or just "Wifi6"? If it states AX200, you have a case. Else, you probably don't - Lenovo doesn't really have a return policy unless it's DOA.
For most cases, it shouldn't matter which wifi chipset you have. However, Intel's wifi has a couple of advantages in a business environment, and is generally the gold standard.
As for Mediatek, they don't yet have a very good reputation. Yet they're happy to announce that they've made it into the Asus ROG.
MediaTek is another name for incredible innovation that powers the brands you love. From smartphones to smart homes, we are always by your side.
www.mediatek.com
Still, this thread suggests that keeping the drivers updated should be okay for most users.