I wish someone would answer your question. As it stands, without any example, I for one have no idea what is being talked about, where these popups in FF are,

I wish someone would answer your question. As it stands, without any example, I for one have no idea what is being talked about, where these popups in FF are, how they affect accessibility. Do I dislike modals that cover the entire window, yes, absolutely, but I have never encountered such in FF as a browser.