This browser lacks WebAssembly JSPI. TeXpresso still works, but compiles the whole document at each change instead of only what follows an edit: slower on long documents. Updating the browser should help; the latest Chrome, Edge, Firefox and Safari have it.
They get them when they open the project again, even if nobody else is online. Kept 7 days after the last change, encrypted with the key of the link, without guarantee: the copy in each browser stays the reference.