I checked the behavior of the program I implemented using the script on the utility page.
In the Test of deleting user data, I confirmed that data can be deleted without problems.
However, when actually deleting a user's deletion request from Moodle and trying it, the data was not deleted.
The status on the data request screen was "Complete". (admin/tool/dataprivacy/datarequests.php)
After confirming the process, "delete_data_for_user" function of my plugin that was not called.
mod_quiz plugin as well.
Do I need to set something to delete user data?