If the number of Items to show in the nestable slider is large (for example 5), this will cause the Border of the first slider to be ignored after scrolling the slider a little. In the screenshot below, the problem is quite obvious. You can also see this bug in the above link.
I guess you mean when you drag the slider with your mouse? in that case thatβs just the expected behavior as the slider gets out of the way no? not sure what exactly is the bug here.