Set a field to Null on update

I have a situation where I have an update server action that is suppose to remove a date and give the field a null value. But when the action is run it sets the date field in the database to 1970-01-01 instead of null.

How can I get it to set a null value to a database field on update?

Screen Shot 2021-06-28 at 2.20.26 PM1952×532 37.7 KB

I even tried setting the field type to varchar but it still adds the 1970 date. Where is it coming from?