According to https://dash.plotly.com/datatable/reference, columns.format is “derived from the d3-format library specification”, which doesn’t have any date-formatting functionality. So that definitely won’t work. If you change the date column of the DataFrame into a string with the format YYYY-MM-DD, before you send the DataFrame to the Datatable, then it will display correctly and sort correctly, because alphabetical order on the string is the same as chronological order.
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