How so? Counties receive plenty of property tax revenue from housing. Due to inflation costs, even with the capped rise in property tax, local governments revenue grows every year. CalMatters has a good article on this effect.

The reason Counties talk about Prop 13 is twofold: local control over tax authority (they can still raise taxes on new developments through a variety of parcel taxes/mello-roos. But they are also being crushed under a variety of other costs the state has shifted to them in recent decades (jails/probation costs, IHSS, pension costs, etc.). Pension costs are the fastest rising underfunded liability for all local governments. Counties want to repeal prop 13 to pay for pensions and cities want to raise sales/soda taxes to pay for pensions.

Unions control of the legislature and the California Rules combine for the pressure/narrative to instead repeal Prop 13 to raise your taxes.

That's a bit simplified so let me know if you want more detail/proof.