We had overlay problems with a fancy <Select> control, also systems like Emotion can have trouble, or anything that is portalized or computes coordinates for absolute positioning. We were able to fix all the ones that affected us.

Funny we have been using the HTML <dialog> because you can't really pass accessibility reviews if you use the modal dialogs that come with MUI, Reactstrap, etc. Only <dialog> really inerts the whole page but you run into very similar problems getting components to work properly inside them which we were able to solve for all the components we use inside dialogs, but I think it's an absolute shame that this has not been adopted by MUI or anything I can find in npm -- what I hate about accessibility is that I feel like I'm held accountable and my organization is held accountable but not the people who write trash specs, make trash screen readers that crash my computer, vendors of React components, etc.