Weird date format in a custom field

One of my clients (companyId=6309971) has a custom field in contacts:

            "id": 9075,
            "key": "e67c5c6acf2abf6c85c4a68a4400bd1b979d8976",
            "name": "activation_date",
            "group_id": null,
            "order_nr": 34,
            "field_type": "date",
            "json_column_flag": true,
            "add_time": "2019-07-12 08:36:32",
            "update_time": "2023-11-09 09:48:59",
            "last_updated_by_user_id": 9566631,
            "edit_flag": true,
            "details_visible_flag": true,
            "add_visible_flag": true,
            "important_flag": false,
            "bulk_edit_allowed": true,
            "filtering_allowed": true,
            "sortable_flag": true,
            "searchable_flag": true,
            "description": null,
            "created_by_user_id": null,
            "active_flag": true,
            "mandatory_flag": false

This field format is really weird when I get a list of contacts or get contact by id (e.g. contact id=1366):

"e67c5c6acf2abf6c85c4a68a4400bd1b979d8976": "2023-01-07 18:38:18.000000,3,UTC"

other date fields look good:

"602c8be68ef2d5d2bf0b11d5cd92d3a78996beb5": "2018-05-31"

Could you fix that?