Here are the results of a quick internet search explaining it from various sources.

Also, if you just look at the FAQ or owners manuals for any induction cooktop out there, they will all tell you the pans have to be magnetic to function. Not "for best performance", to function at all.

It really sounds like you are thinking exclusively of induction forges, which can heat non-magnetic materials. Induction cooking hobs absolutely cannot heat non-magnetic materials to any noticeable or useful degree, they do not have the frequency range or the power for eddy currents alone to be sufficient. Induction forges on the other hand HAVE TO have the power to heat with just eddy currents because if you heat iron or steel up to glowing, it loses magnetism (and the heating slows significantly past that point).

https://kindle-tech.com/faqs/what-materials-can-be-induction-heated

Ferrous metals (like iron, nickel, and cobalt) have an additional, more powerful source of heat.

These materials are composed of small magnetic regions called domains. The alternating magnetic field from the induction coil causes these domains to rapidly flip their polarity, billions of times per second.

This rapid flipping creates immense internal friction, which generates significant heat. This hysteresis effect is what makes ferrous metals heat so much more quickly and efficiently than their non-ferrous counterparts.

https://axiomht.com/blog/how-does-induction-heating-work/

In ferromagnetic materials like iron and steel, a second heating mechanism kicks in.

As the alternating magnetic field repeatedly reverses the magnetic domains within the material, the friction generates additional heat known as hysteresis losses. This effect disappears once the material crosses its Curie temperature (around 770°C for steel), at which point ferromagnetic properties are lost. Above that point, eddy currents carry the full heating load. For industrial heat treatment of carbon steel, both effects work together in the lower temperature ranges, delivering faster heating rates.

https://en.wikipedia.org/wiki/Induction_heating

In ferromagnetic and ferrimagnetic materials, such as iron, heat is also generated by magnetic hysteresis losses.