Assalaamu alaykum. Here at our local masjid, there is a tendency that whoever has a problem, like sickness, drought, etc., comes to the imam and asks him to request the believers to recite Surat Al-Faatihah for them after the prayer so that Allaah, The Exalted, may sort out the problem. Is this according to the Shariah, or is it just a fabrication?
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
Specifying the recitation of Soorah Al-Faatihah in the hope of solving problems and so on is something for which there is no evidence in the Quran or the Sunnah of the Prophet .
Therefore, it is feared that the action of that imaam could be included in innovations. So you have to advise that imaam and clarify to him that relying only on what is Islamically confirmed and proven is better and leads to good consequences.
If someone asks him for supplication, then he may supplicate for him without especially reciting the Faatihah or any other Soorah.
Allah knows best.
You can search for fatwa through many choices