Help needed for using date subtraction in an automation

[Jaqueline Mendes]

Hello guys,
I need help with an automation task. In my workflow, I use epics, and I need to track changes in the due date. Whenever there is a modification in the due date of a card, I need to retrieve the previous date and calculate the difference between the previous date and the new date. For example, if the date on the card was 06/22/2023, and I changed it to 08/22/2023, I would like to identify the difference, which in this case is 2 months. Is there a way to accomplish this automation without adding plugins?
I appreciate any assistance you can provide. Thank you in advance.

Important: I have managed to save the previous date and the new date in a variable using automation, but I am having difficulty in calculating the difference between these dates. I have tried some functions, but I have not been successful.

[Ojase Emmanuval]

I have used the following smartvalue to calculate the difference between created date and due date.

{{issue.created.diff(issue.duedate).days}}

You can use something similar. When you copy the old and new values to variable, please make sure you are parsing the value as date and not string.