Hi,
It happens, because the search input is placed into a sticky header container (fixed position), and the results box follows the search input field.
For that, try limiting the maximum height of the results container for the mobile and tablet devices, like this: https://i.imgur.com/CoMqyvX.png
You may need to experiment a bit to get the best size, but around 65vh should be the best in your case. After making the changes you will have to clear all layers of cache to see the change.