Thanks for reaching out to the Auth0 Community!
That is correct. The Post Password Change Action event object does not have any way to call the user’s user_metadata.
As a workaround, you could use the Management API to accomplish this. Please take a look at the How can I use the Management API in Actions? FAQ to learn how to do so.
Once that is complete, you can call the ManagementClient getUser method to get the user’s user_metadata.
Hoped this helps!
Please let me know if you have any additional questions.
Thank you.