AMD says overclocking blows a hidden fuse on Ryzen Threadripper 7000 to show if you’ve overclocked the chip, but it doesn’t automatically void your CPU’s warranty::AMD explains the hidden fuses behind Ryzen Threadripper 7000 processors and how it will handle warranty claims.
I think they’d scale well so it wouldn’t have that big of an impact. Like it could be one set of fuses for the entire chip. Even a KB of those fuses wouldn’t take up much area on modern chips. That’s if they are detecting settings or overall chip power.
If they are detecting OC damage to circuitry, that might involve a lot more fuses throughout the chip along with circuitry to read them (or at least detect their state), which could be more involved. Though there is already circuitry to test the functionality of the chip at a fine level for binning and QC, and it might be trivial to add some fuses to that.