A better idea would be to use custom inputs that produce "typos" that the user didn't make. E.g. you have a "zip/postal" code field and your input sneakily swap

A better idea would be to use custom inputs that produce "typos" that the user didn't make. E.g. you have a "zip/postal" code field and your input sneakily swaps 2 neighbouring characters at some point, resulting in error "this zip code doesn't exist". Or change 8 to 9 etc. Or you could make a "check your input one more time before confirming" step and display typos in e.g. names/emails there.