I make Qur’an recitation clips for YouTube using AI-generated landscapes. For verses about Jannah, AI creates gardens, while for punishment/Jahannam it creates fire or lava. Is it permissible to make and upload such videos?

It is not allowed, these images are not even comparable to what is in paradise or the hellfire, and the fatwa of the scholars is that it is not permissible to do so. Keep uploading beneficial things just change these backgrounds.