Between 5.16 and 5.24 are about four years of development, so there is some potential for differences in behaviour.

Can you maybe show us examples where the code behaves differently? Otherwise, all we can do is to point you to the documentation of the differences from 5.16 to 5.24: perl518delta, perl520delta, perl522delta and perl524delta.

In principle, all incoming data is tainted. Taint mode trys to address what you (try) do with that tainted data. Maybe there are some code branches that do not get executed on Windows that do something dangerous with the data? We can only guess at this point in time.