Widget scrolling 'glitch'

Hi,

The plugin works well, except when there is not much content on the page, the widget jumps to the top of the page when you scroll back to the top

See the following pictures:

Before being scrolled:

After being scrolled:
http://dixfractions.com/solen/wp-content/uploads/bad.png

Thanks in advance for your help!

https://ww.wp.xz.cn/plugins/q2w3-fixed-widget/