Hi Ben,
As I said above, it just based on behavior of the field, no relationship of format.
Why three ‘date only’ field just one can be shown in the rollup wizard?
Because the other ‘date only’ field just format is ‘date only’, but behavior is ‘user local’, These two ‘date only’ are different concepts.

In the page, the data type shows the format of the date field, not behavior.

Regards,
Leah Ju
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