I wanted to report this as a bug, but Report a bug took me to Gethub so I didn’t want to think a lot 
It took me a while to figure out what is happening!
Just add a scroll view, put a loop to add any objects to the scrollview like text objects ( I added a sample code just run with enabling or disabling the front and back commands and see the effect
scrollviewbug.zip (66.3 KB)
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If you set objects to go to back using this method :toBack()
The scollview will add empty spaces at the bottom, and it will not bounce back when you reach the last object, it will keep scrolling until you reach the end of the empty spaces which were added
if you use :toFront() this does not happen … it happens only with :toBack()
But what is strange is that if you use ScrolltoBottom it will scroll to the last object, but if you scroll with your finger it will keep going down