Hi Hosein,
Depending on the available space, the dropdown content either opens to the right (if there is enough space) or to the left (if there is not enough space).
It does this by using JS to calculate whether there is enough space when the page is loaded. If there is not enough space, we add a class to change the position of the dropdown content. This normally takes about a millisecond and results in the scrollbar you show in your video when loading.
However, you can avoid this problem by setting the “right” value of the dropdown content to 0. Then, regardless of the calculation, it will always align itself directly to the right edge.