With the mobile editor, try previewing it and click on the show more and show less button, then with it back again on the show more option, go back to the Wix Editor and see if the white gap is still there. If it is shown on your Wix Editor then you can see if you need to re-arrange your elements to remove the white gap.
So basically…
View your preview with the show more button as it is and then click back on Editor to go back to the page with the short text function and see if white gap persists due to the elements being setup on the page at full text size…
Or view your preview and click on show more to view the page with full text and then click back on Editor to go back to the page with the full text shown.