Using the rather new backdrop-filter CSS property can lead to a crash of the entire iOS on an iPhone. An exploit that does this and the code behind it have recently been unveiled by a software engineer and security researcher at Wire. The even worse part is that this issue might affect macOS-driven systems as well.
https://www.notebookcheck.net/Defective-CSS-code-crashes-causes-iPhones-to-restart.332380.0.html