Additional Compensation and Conflict of Interest

My understanding is that an additional compensation requirement isn’t a conflict of interest only if the additional compensation is from unrelated work (and not investment research/advisory related). Firstly, is this understanding correct?

Secondly, if the work is related, is it always a conflict of interest? What if the two “jobs” require a person to cover completely different security types (equities and bonds, maybe?) or completely different sectors?

Thanks!