stickyStop error when custom scrollEl and the content has large scroll content

[athena0304]

Requested Update

Why Is This Update Needed?

Are There Examples Of This Requested Update Elsewhere?

https://codepen.io/athena0304/pen/qzWpqP
In this demo, I enlarged the height of article, as scrolling down, the sticky element became to be js-is-stuck so early, which was supposed to be js-is-sticky.
So I suppose to change parentBottom's parent.offsetHeight to parent.scrollHeight

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