UPDATE September 08, 2021: We were able to solve the issue, the fix is live already! We are also testing with iOS 15 and haven't found any problems yet!
---
Since the update of iOS devices to version 14.7.1 the scrolling of the left sidebar is not working perfectly anymore. This seems to apply for all browsers, but not only Safari.
We are working on this and we will try to find a solution as quick as possible!