Some Shia told me that Imam Mehdi and other Imams see and hear everything exactly the way that Allah does and they use justification that "it is Allah who gave them that power". I simply don’t understand this concept. I understand Imamate and it’s importance but this seems like a really far stretch for me. Is this true and if so then why?

No doubt they are chosen by Allah
All power and qualities are Granted by Him only
Source is Allah and provider is Allah they are Hujjat and proof of Allah but Allah is Allah you can’t say that both are equal in seeing and hearing.