Sprout Email: object variables will not resolve in text and redactor field since upgrade
This is expected behavior. This feature was changed due to a security vulnerability and is mentioned in the upgrade notes.
To create similar behavior you will need to confine your dynamic variables in the Control Panel to the Subject or Default Body fields. Any other custom variables will need to be added and managed in a custom email template.
We will consider adding back improved functionality in the CP workflow if we can find a way to do it safely.