It may be strange to consider this as a spiritual practice but every Christian serves as a watchman for the Lord. We are to expose the works of darkness in the world with the light of the truth of Jesus Christ (Ephesians 5:11). I do not know that this necessarily mandates that all Christians be whistleblowers in certain senses of the word but if we see someone doing something that is wrong and we have warned that person or the Lord indicates that such a person will not heed our warning then we should bring the attention of this to the appropriate authority. While Proverbs 30:10 tells us not to slander an employee to his employer, slander is telling a falsehood and so this does not prohibit blowing the whistle where needed.
I do think there is judgment that needs to be exercised as to what matters can (and perhaps should) be covered (for example errors in judgment or venial types of sins) and what matters should be brought to the attention of those in authority but this is where it is important to exercise discretion and pray for the Lord to guide us. I have personally made calls both ways and I suppose it takes experience but one strong guide is whether or not our conscience condemns us if we don’t say something. We are to keep watch and are the eyes and ears of God. We also bear responsibility if we don’t say something when we could have.