I recently heard that we are not allowed to offer private dua with raised hands at the time of iftar (i.e. when Maghrib time is about to enter. Is this true?

Answered according to Hanafi Fiqh by Darulifta-Deoband.org

بسم الله الرحمن الرحيم

(Fatwa: 1189/919/H=10/1434)

There is no harm in supplicating silently and individually at the time of iftar. It is right without any karahat (undesirability), rather it is good. Not known from where you heard that?

Allah knows Best!

Darul Ifta,
Darul Uloom Deoband