MAUI doesn't seem to have Linux support for now. There are some community efforts but nothing here yet. That pretty much kills multiplatform aspect. At least for category of server management tools where my product belongs. Ok, Win + Mac is better than Win only, but if I have to redo entire app it should better support Linux as well.

Also, it's hard to bet on a new MS GUI framework, when they released and abandoned several in the last decade. Will it be supported in 5 years as a minimum? Yes, Winforms looks outdated, but it still builds and works as it did back in 2005.

One more thing, I'm not using vanilla Winforms but also excellent DevExpress controls. For example Winforms has a grid, but DevExpress grid is highly customizable, works ok with 100k rows, has filtering, sorting, etc. It's not only about base GUI framework, it's also about entire ecosystem of GUI controls. And maturity of these controls. E.g. Devexpress has MAUI grid, but I don't expect is to be as mature as winforms one.

I'm not saying that MAUI couldn't be useful for some cases. Even many cases. It's just not yet ready for my kind of software.