There are three answers, so normally I would refrain from writing my own. However, I note with some displeasure that none of those answers actually answer OP's question as asked:
How would different ethical frameworks draw boundaries on when it is ethical to criticize an entity?
So, let's quickly run through some of the more popular options.
Consequentialism and Utilitarianism
Under a generic consequentialist framework, the relevant considerations are the consequences of the criticism. Will it motivate the subject of the criticism to do better in the future, or will it simply anger them? Might the criticism positively or negatively influence the behavior of others?
Act utilitarianism continues this by claiming that the specific consequence we care about is the total happiness or utility resulting from the criticism. Then, we need to balance the net good that the criticism delivers to society against the feelings of the individual being criticized. This must be done on a case-by-case basis.
Rule utilitarianism, on the other hand, would prefer a more abstracted approach. It will tend to develop broader rules about when and how criticism tends to benefit society overall, and then stick to those rules rather than trying to do everything from scratch in each case. A rule utilitarian would likely look to the validity of the criticism, as well as how effectively it is expressed. Note however, that we are not looking to these factors because they carry any moral weight. Instead, we are looking to them because we believe they are related to the likely consequences of the criticism.
Deontology and Kantian Ethics
Deontology is about duty. When considering the moral ramifications of criticism, the first question is whether it advances or interferes with some moral obligation. For example, a movie critic is hired by a newspaper to produce accurate and useful criticism of recently released films. If the critic refrained from criticizing a film that deserved it, that would be an abrogation of their duty to their publishers and their readers. They would be accepting payment without doing their job properly.
Kantian ethics goes quite a bit further, and ultimately arrives at the conclusion that lying is morally wrong in all circumstances. So the Kantian would certainly endorse truthful criticism of any variety, if the alternative is to lie. However, saying nothing at all might better adhere to the categorical imperative, depending on the circumstances.
The likely consequences of the criticism are irrelevant. We only care about how and to what extent the criticism fulfills or violates our moral duties.
Virtue ethics takes the approach that good actions are those which exemplify specific virtues. Truthful and politely-worded criticism exemplifies a number of "classic" virtues, including honesty and respect. On the other hand, a rude or dismissive form of criticism would exemplify vices and be categorized as morally wrong. The same could be said of invalid or false criticism.
Again, we don't care about consequences, or even duties except insofar as they can be related to virtues such as integrity.