Should anything concern me if I want to upgrade from vue2 with `vue-property-decorator` (class style) to vue3?

I have the same problem with one of my projects. We wanted to use TypeScript with Vue2 and the property decorator was the best way to go, but migrating means, you can't do it gradually component by component, you have to refactor all of them as this approach is no longer supported. I'd recommend to refactor the components to use the composition API, with a bit of work you can even migrate potential mixins you have to composition functions.

In short it means a lot of work, without the property decorator you probably could migrate way quicker.

EDIT:
I just found out that people are working on a Vue 3 version of the property decorator, but rely on the class component. You can read up on this interesting thread: https://github.com/vuejs/vue-class-component/issues/406