The documentation on both the Gallery and Data Grid 2 has a short sentence that should be more prominent in telling developers about a crucial limitation of the widgets, namely: using 2 or more of the same filters does not work as separate filters, they will be treated as 2 inputs for the same filter.
The app I'm working on uses the Gallery widget with styling to create a beautiful presentation of multiple layers of data. But the client can't search/filter on 3 separate string-attributes due to the widget limitation. Our options now are to rebuild the search functionality and use OQL along with unique attributes for the filters or ask Mendix to improve the current functions. Our first option simply introduces more complexity for something that was previously possible with a Data Grid.
Linking to 2 other ideas that are related: https://forum.mendix.com/link/space/studio-pro/ideas/3340
and https://forum.mendix.com/link/space/widgets/ideas/2856