What is the reason for feeling the sins of others, despising them, showing favor to Allah, and feeling hypocrisy and relapse?

Despising others and showing arrogance towards them is a form of pride for which Allah has threatened its perpetrator with not entering Paradise. You overcome this by reflecting on your own sins and shortcomings. As for showing favor to Allah (al-mann ‘ala Allah), it is among the actions that nullify deeds, and it is overcome by recalling that all grace belongs to Allah. Hypocrisy (riya’) is overcome by striving in worship and purifying the heart. Relapse (intikasa) is avoided by holding fast to the rope of Allah, supplicating Him, trusting in Him, keeping company with the righteous, and increasing in acts of worship, while being wary of the whispers of Satan that might delude you into believing you are showing off.