Sometimes I find Field filters appearing like this:
and sometimes like this:
I never understood how I got the check box list, and now I am even more puzzled since these two filters are from the exact same data source, only in two different dashboards. This is how the field is defined:
Sometimes I would like a checkbox list, because of its particular usability in deselecting certain items. How can I control how the list appears?
I totally understand your confusion.
You are most likely using a dashboard filter on multiple cards, which has different datasets. Up until a couple of versions ago, you would not even see a dropdown in such cases, but that was fixed - but that introduced the old checkbox dropdown-style in some cases.
The checkbox dropdown is from before version 0.28, if I recall correctly.
There’s an issue open about the switching styles:
https://github.com/metabase/metabase/issues/10570 - upvote by clicking on the first post