We are working on providing you with tools to display more items in a gallery while not sacrificing site performance.
As part of this effort, the dataset will control the number of items a gallery displays at once. To do so, set the 'Number of items to display' in the 'Dataset Settings' panel.
What you need to do:
If you currently have a gallery with more than 20 items displayed, the gallery shows all its items at once. Beginning Wednesday 7am EST, the gallery will only show the first 20 items by default. If you want to show more than 20 items you need to set the 'Number of items to display' in the connected dataset.