Geometry Collections can be very difficult to intercept. They sometimes are nothing ore than a fairly simple polygon, where one of the segments is an arc for example. Trying to write these to quite a few formats usually results in problems, and some GIS applications like QGis can’t handle them properly.
But there is no surefire way to catch these, since they are not always aggregates. There have been a few threads about this already, like this one: Geopackages and different polygon types in same layer ? | Community and this one: Aggregated surfaces written in wrong file format in SQL server | Community
It would be very helpful if the option ‘Collection’ was added to the GeometryFilter’s Simple definition list. It might already be possible using the Detailed mode, but that is not very obvious (I haven’t figured out how...).