[gruez]

>my phone locks up for a moment with a black screen and spinner and then I have to unlock the phone

AFAIK that happens when springboard crashes. Maybe there's a 0day exploit in there?

[simongr3dal]

When taking a screenshot in safari on iOS 13 it also tries to save a pdf of the entire page. If you open the little screenshot overlay in the corner there is an option to save as the full page as pdf instead of a screenshot.

Maybe the pdf is just too big to be re-rendered and saved as a new pdf and it crashes somehow.