Multi step form using React, Typescript and MUI Joy

I used MUI Joy component library for this challenge, and that means that some components differ a little from initial design. I chose it because MUI library offers production-ready components that cover a lot of edge-cases, and I wanted to try its' Joy version.

One thing I haven't solved yet, is a peculiar Checkbox behaviour: it changes value in one direction, but not in another, meaning that a user can "uncheck", but can't "check" it. If you can help with it, I'd be grateful.