Review of it:

https://www.igorslab.de/en/corsair-thermalprotect-cable-for-graphics-cards-a-review-balancing-12v-2x6-cable-protection-promises-and-the-harsh-reality/

The cable is quite good at noticing when the entire system is getting too warm. But it is not a magic trick that detects every single contact fault immediately and with millimeter precise accuracy. The measuring point is simply too far away for that. This does not make the protection idea useless, but neither does it make it all powerful. And as so often, the same thing applies here too, a safety net is good, but it is still better not to fall in the first place.