The simplified validation_output dictionary generated by the custom callback should only contain failing and warning tasks. When gathering fact, the task result always contains a warnings key set to an empty list. In conclusion, the task logs related to the gathering fact action are included in the simplified output and it should only be included when there is actually real warnings.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Red Hat OpenStack Platform 16.1.3 bug fix and enhancement advisory), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2020:5413