Fervo uses engineered reservoirs in granitic basement rock so this is less of an issue. Hot rock in a working fluid can still dissolve silicates out of the granite and lead to scaling / degradation of the flow rates through the reservoir and that is a risk but chemical anti scaling treatments are used to reduce this.

CA has the worlds largest geothermal power complex in the Geysers. That one field produces an equivalent amount of power as all the geothermal in Iceland and there are others.