Maybe I am using the wrong name for it.
To the right of the url near the top of the screen there is often a small hamburger-like icon with a tiny A in the top left corner. The function simplifies most pages for easier reading.
Actually the problem exists in regular mode as well as well.
There is no select all function and when I try to manually select the text in an article (and images, too) I can only get a couple of paragraphs. There is no way to extend the area selected.