Bukhari

Hadith Commentary:

This is the very characteristic of the friends of Allah; in contrast, worldly, gluttonous people sit down to eat and begin to find faults with every morsel. May Allah the Exalted grant every Muslim the ability to act upon the example of the Messenger (sallallahu alayhi wa sallam).
(Ameen)

Hadith Commentary:
This is the characteristic of the friends of Allah that they never find fault with any food. In contrast, worldly people and gluttons, when they sit to eat, begin to find faults with every morsel. Among us, it is a common practice that while eating, complaints about the lack of chili or salt begin. In the light of the beautiful example of the Messenger of Allah (sallallahu alayhi wa sallam), we should examine this behavior of ours.
And Allah knows best.

Hadith Commentary:
It is understood that mentioning a defect in the food, such as saying, "There is no salt in it," or "It is bland," or "There is too much salt,"—all such statements are disliked (makruh).
However, correcting a deficiency in the cooking or preparation is not disliked (makruh).

Hadith Commentary:
(1)
What is meant here is lawful (halal) food, because condemnation of eating unlawful (haram) food is established from the Messenger of Allah (sallallahu alayhi wa sallam). That is entirely blameworthy. The Messenger of Allah (sallallahu alayhi wa sallam) would condemn it and prohibit eating it.

(2)
Some scholars are of the opinion that it is prohibited to consider food blameworthy on account of its natural form, but it is permissible to criticize prepared food. However, the wording is general, and in no case is it correct to call it blameworthy, whether in terms of its making or preparation. In this way, the morale of the one who prepared the food is diminished. Imam Nawawi (rahimahullah) says that among the etiquettes of eating is that faults should not be found in it, such as saying it lacks salt, is bland, has too much salt, or its broth is not well-cooked. All these things are disliked (makruh). However, correcting a deficiency in the cooking or preparation is not disliked (makruh). (: Fath al-Bari: 9/678)

Benefits and Issues:
➊
A person cannot do without eating from the blessings of Allah.
And then to find fault with it as well—
this is a very bad trait.
If there is any shortcoming on the part of the one who prepared the food, it should be explained to him in an appropriate manner.

➋
From this hadith, it can also be deduced
that if a person has made an agreement with someone or with an institution,
and the matters and conditions agreed upon are being followed, then it is not appropriate to unjustly criticize or reproach that institution or those individuals.
Either fulfill the relationship with goodness and harmony, or part ways in a good manner.
However, the Islamic, legal, and moral right of giving advice and wishing well should be fulfilled in a good way.