may be truncated if it exceeds the maximum length of 4000 characters
This is a validation message based on SSIS not knowing if the result of an Expression in your Package will be exceed 4000 characters in length and be truncated at runtime. This is because the result of an Expression depends on runtime value of the involved Variables, i.e. the data, which SSIS cannot predict. What do you have for Execution Options in your job?
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato