[Vuejs]-Bugs when applying intersection observer in VueJs

I think your problem is related to the threshold you have set. I recommend reading: https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API

Treshold:

Either a single number or an array of numbers which indicate at what
percentage of the target’s visibility the observer’s callback should
be executed. If you only want to detect when visibility passes the 50%
mark, you can use a value of 0.5. If you want the callback to run
every time visibility passes another 25%, you would specify the array
[0, 0.25, 0.5, 0.75, 1]. The default is 0 (meaning as soon as even one
pixel is visible, the callback will be run). A value of 1.0 means that
the threshold isn’t considered passed until every pixel is visible.