This usually happens when the server has a newer version of thw Pulse Client. I recommend to check with your internal team for any changes in the Pulse Connect Secure VPN appliance.
The latest version of Pulse Desktop Client 9.0R3 is 64-bit compatible. From our understanding, Apple has not made any final decisions to block 32-bit client and providing the message as a warning to end users.
This has nothing to do with an update from the server. This is a macOS waring that the next version of the macOS will not run 32-bit apps.