The people in Gaza are hostages which are being denied access to most basic essentials like food, water and medicine.

They are being exploited to beg friends and family for money so that they can purchase these necessities at exorbitant prices from their captors.

UNRWA get's 12$ from donors, purchases a bag of flour and delivers it to the Israeli authorities at the border crossings into Gaza.

The people in Gaza then have to collect 600$ from their supporters to withdraw 300$ to purchase that bag from a local merchant.

300$ withdrawal fee are probably split between some "money changer" in Gaza and someone who can bring money into the strip, probably IDF personnel.

300$ for a bag of flour are probably split between the merchant in Gaza and someone looting the aid waiting at the crossings.