This recently happened to me when I was using an online website for preparing for a drivers license test. After finishing a 20 question practice test, the site would show a cool confetti animation on top of everything. While cool, it would prevent any clicks from registering on the entire site for the entire 5 second duration of the animation. I emailed the company to add `pointer-events: none;` to the confetti `div`. That fixed the problem.
Since the website had been around for a very long time, I wonder how many millions of seconds had been wasted on this animation to complete.