The scrollable-region-focusable is currently at moderate. I think we made a mistake there, this can result in people unable to view content they need to view. Setting it to serious makes this consistent with the impact of frame-focusable-content, which is very similar.

While problematic, I don't think this quite reaches the level of critical, because copy/paste can still get you the content, and some clever use of a browser's search function can also function as a work-around.