What is the ruling on concealing advertisements within an application and profiting from them, given the difficulty in controlling their content and their remaining unseen by the user?

Hiding advertisements goes against their purpose, which is for people to see them. This is considered cheating, deception, and taking money unlawfully, as the Prophet, peace and blessings be upon him, said: "Whoever cheats is not from me." If controlling the content of advertisements is difficult and they are predominantly unlawful, then one must avoid this field.