QPWDLVL 4

I'm looking at following the steps to check for readiness to go to QPWDLVL
4 as outlined at
https://www.ibm.com/docs/en/i/7.5?topic=changes-considerations-changing-qpwdlvl-from-2-3-4

Part of my concern is that they mention:
"Any client that uses password substitution will not work correctly at
QPWDLVL 4 if the client hasn't been updated to use the new password
substitution scheme. The administrator should check whether a client which
hasn't been updated to the new password substitution scheme is required."
then they proceed to list some valid clients.

Anyone have a list of clients of concern?

We do NOT support/allow unsupported versions of Windows.
We do NOT support/allow the old Client Access.