If I always say the adkhar of the morning, evening, when leaving the home, coming back home, entering/exiting the toilet, eating food, going to bed, and am still harmed by people, then what is the cause of this? My own negligence when saying the adkhar? My sins? Feeling confused & very disheartened

How do you know that Allah did not protect you from evil that was going to befall you by saying the adhkar? The adhkar are a means of protection, and their effect is weakened by a heedless heart and by sins, but harm still reaches the prophets and the righteous to raise them in rank, so it does not mean your adhkar were rejected. Keep saying them with presence of heart and certainty, and do not despair.