You might find solace in the special variables presented by Automation Controller / AWX like awx_project_scm_branch and awx_job_scm_branch. You could bake that into how you evaluate the no_log task parameter.
- ansible.builtin.debug:
var: my_sensitive_var
no_log: >-
{{
true if awx_project_scm_branch == "main" else not ansible_verbosity
}}