100iso on full frame does not equal 100iso on aps-c. The numbers are the same but the actual amplification on iso is not transferable across cameras.
You can see this by looking at noise of the same ISO number on different size sensors, there would be more noise on smaller sensors.
https://photographylife.com/equivalence-also-includes-aperture-and-iso#iso-and-equivalence
100iso on full frame does not equal 100iso on aps-c. The numbers are the same but the actual amplification on iso is not transferable across cameras.
You can see this by looking at noise of the same ISO number on different size sensors, there would be more noise on smaller sensors.
https://photographylife.com/equivalence-also-includes-aperture-and-iso#iso-and-equivalence