I took a quick look at the book at Chapters as I had to cancel my order because of money issues, and I noticed Strixhaven also refers to nor only the Feywild, but directly says also that Witherbloom students draw their magic from the Negative and Positive Energy Planes. Is this book MtG canon?

If they keep this up they will either have to create D&D parallel versions of Theros, Ravnica, Arcavios, and maybe Kamigawa, etc..., or merge the settings otherwise fans are just going to get more and more confused. I think creating parallel versions will create less backlash then merging and the MtG Netflix cartoon is going to create their own versions of the MtG worlds, so no reason D&D can't.