If user navigates from and back to a page with .animate-in elements quickly, the animated elements in the page disappear

[vezwork]

Repro steps:

• go to page-0
• press NEXT to go to page-1
• immediately press BACK to go back to page-0
• observe that the elements in page 0 are not visible.

This occurs because of the following code:

setTimeout(() => {
    animatedEl.style.opacity = 0;
}, 800);

It is very unlikely that a user will encounter this problem, as you have to move your mouse very quickly and intentionally to go back fast. It is also easy to recover from this problem, just press next to go to the next page.
So I am marking this bug as an enhancement.