What is the advice for someone suffering from the trait of ingratitude towards those who do him a favor, due to being raised in an environment that heavily reminds others of their good deeds and his suspicion of others' intentions?

The one who gives a gift should be rewarded with a similar or better gift, with supplication and praise. It is not permissible to deny recognition to those who deserve it. The Prophet, peace and blessings be upon him, encouraged this, saying: "He who does not thank the people does not thank Allah." Gratitude is expressed through kind words, supplication, and reciprocation. Islam forbids entertaining ill thoughts about people. Therefore, a Muslim must strive to abandon bad assumptions and interpret the actions of those who do them a favor in the best possible light.