What is the solution to the problem of secretly committing sins, such as looking at pornographic websites and masturbating, despite outwardly appearing committed and participating in da'wah activities, and feeling hypocrisy and pretense, and repeatedly repenting then returning to the sin?

The fear of Allah and His constant observation safeguard a servant from error and lead them to Allah's pleasure and Paradise. Do not be among those who fear people but do not fear Allah. Avoid being among those whom Allah will bring forth on the Day of Judgment with good deeds like mountains, only to render them as scattered dust because, when they were alone, they violated Allah's sacred limits. Lowering one's gaze from forbidden things protects from many sins and has three benefits: the sweetness of faith, the light of the heart and perception, and the strength, steadfastness, and courage of the heart. If you fall into sin when alone, hasten to repent and seek forgiveness, and do not despair. For the righteous, when an evil thought from Satan touches them, they remember [Allah] and immediately become insightful. Allah forgives sins, no matter how many times they are repeated, as long as you sin and then repent. Every son of Adam is a sinner, and the best of sinners are those who repent. Follow up a bad deed with a good one, and it will erase it. Do not let your sins prevent you from inviting to Allah, for Allah helps a servant as long as the servant helps his brother. Strive against your ego for sincerity and avoid showing off by seeking refuge in Allah from polytheism. Increase your reading of books related to purifying the soul and the states of the Hereafter, and the recitation of the Quran and remembrance of Allah, for this protects from Satan.