"GMO" is the Gaza Media Office, meaning Hamas.
OCHA claims the 33,797 figure comes from the ministry of health. The MoH does parrot the Hamas figures every day. But it also releases detailed reports every few days of deaths they consider to be verified, which include breakdowns of women, children and elderly,
It is literally impossible for both sets of numbers reported by OCHA to be correct.
The detailed MoH reports say that they have verified 22,397 deaths, of which 11,847 are women and children (4,642+7,205.) According to Hamas and the UN, there are a total of 24,000 women and children killed.
The difference between the number of women and children counted between the two sources (12,153) is higher than the total difference of all deaths between the two sources (11,400.)
Hamas is provably lying - and the UN happily repeats their lies and gives them credibility. The UN reports then get repeated by other UN agencies, media and NGOs as authoritative, notwithstanding the small text on the bottom of the OCHA reports saying "The UN has so far not been able to produce independent, comprehensive, and verified casualty figures; the current numbers have been provided by the Ministry of Health or the Government Media Office in Gaza and await further verification." That isn't good enough: once we know the Hamas GMO is lying, it is irresponsible and libelous to give them any further credibility.
And this has been going on for a long time. The MoH had divided up its "martyrs" into two categories for months - the ones it could confirm and the ones it repeated from Hamas. Both sets have been inconsistent with each other and with Hamas claims of total women and children casualties, but OCHA still always used to unreliable numbers in their headlines.
But, hey, this is the UN we are talking about, where the most outlandish anti-Israel lies are treated as gospel.