If you're talking about the python cryptography fiasco that was dropping support for S390 (31-bit architecture discontinued in 1999). S390X (64-bit architecture introduced in 2000) is supported by Rust, though not necessarily by Python Cryptography.

Incidentally Rust's continued support for S390X is driven primarily by cuviper who works for Red Hat (even before the IBM acquisition).

But s390x support isn't dropped anywhere. On the contrary, IBM spends a lot of money and efforts to make sure it is well supported by free software.