When you click on the brand names, the filter is triggered and the scroll is triggered at the same time. You can remove this scroll in the file z__jsCollection.js. To do this, find the word scrollToTop in this file and try deleting it http://joxi.ru/J2b9Rv0i0axx8m.
After you delete it, this unwanted scroll should disappear.
To do everything, you need to go to the Online Store->Actions - >Edit Code. Then enter z__jsCollection in the search field http://joxi.ru/12MBOXLIlJq4kA. Open the file and look for scrollToTop. To do this, use hotkey cmd+f or ctrl+f. scrollToTop is in two places, in both places you can delete it.
Or just replace the contents of z__jsCollection.js on this one https://codeshare.io/ax9vdD. Here we have already removed scrollToTop.