correct, the restrictions of the environment are lifted, but the restrictions of the associated services are not. So the task queue service still has a payload size limit, as that is an off-instance service. (similarly the max size of an entity in NDB is still the same).
i can't find the docs right now, but i think the payload size is around 1MB, but might be completely wrong. the new documentation structure hides a lot of these details that were easy to find in the older docs.