The Gaza ministry that would have counted the deaths was also destroyed several months ago, which is why news media have been reporting the same death total of 40,000 for several months.
This is wrong. They are still reporting daily deaths counts, that counts have been going up. The Grauniad is good about collecting the reports (but bad about other unrelated things).
The Gaza heath ministry's figures remain the best (and basically only) source of casualties to date. While they're no longer able to record many deaths in hospitals or morgues, they've adapted by collecting casualty reports from other sources like a Google form (which makes the data a bit iffy, but better than nothing).
It is a report that was correctly widely criticized. Certainly worth reading, but worth being aware of this.
(I personally think that estimating that the eventual death toll will be 4x higher than the somewhat-verified death toll that exists today, based on guesses of the impact of the war on the population, is very disingenuous and misleading, and mostly a way to just be able to say much higher numbers.)
It wasn't "widely criticized", it's taking into account the starvation, attacks on hospitals... estimating how many people are going to die is important work.