> 30,000 Hamas fighters
those are different things.
A very significant part of the claimed number of deaths in my opinion
67000 is, for the record, an underestimate, as the only recorded deaths are ones that happen in hospitals. With Israel's indiscriminate bombing campaign, many have been lost under rubble, and with hospitals being bombed, reporting has slowed down in the last year while the genocide has continued to become worse.
This was only true early in the conflict; Hamas has long since been adding in casualties reported by "reliable media sources" as well as a Google form.
They later moved to a self-hosted form, which remains available to anyone who wants to report a purported casualty: https://sehatty.ps/moh-registration/public/add-order
This has been well known since early last year, when Hamas themselves spoke about their incorporation of these other sources.
Casualty reports slowed down presumably because the fighting slowed down; in any case it's not a reason to make assumptions about Hamas' methodology that are contradicted by easily verifiable facts.