I agree with your spirit, just mentioning that on S18 you were able to remap it, and on S20 there's no special Bixby button just the power button whose bixbyfic

I agree with your spirit, just mentioning that on S18 you were able to remap it, and on S20 there's no special Bixby button just the power button whose bixbyfication can be disabled (together with the entire Bixby). But could your problem be a country- or operator-specific "feature"?