I see downcasting issue.
You are sending User object where TenantUser is expected. And application failed to downcast the User object to TenantUser object.
Upcasting is always done automatically. Meaning, when you pass TenantUser then it can be converted to User.
Did you by any chance also changed the Microflows and/or other actions for widget to use TenantUser.
If so, this is not needed. You can use User and safely TenantUser.
To fix this, you could revert your changes within the appstore module and keep the User entity. This is safe, because, it helps to easily update the widget in future.
Or, you could also cast the User object being passed to a TenantUser.