Is it permissible for a person who abandoned the internet for the sake of Allah due to pornography to return to using it after seeing many benefits in it, and what are the consequences of that?

The internet has both benefits and harms, and it can be used for spreading knowledge and da'wah (inviting to Islam). Whoever abandons it out of fear of prohibitions, such as pictures of women, will be rewarded. If one returns to using it for a permissible purpose, there is no harm, and one must fear Allah and avoid prohibitions as much as possible, in accordance with the Almighty's saying: "So fear Allah as much as you are able."