I have a pluggable as well, but I haven't done the upgrade (mainly because of your report). But I see others reporting this issue on the DisplayLink forums :
https://www.displaylink.org/forum/showthread.php?p=96874
One user (colorcritical) claims to have got it to work (does he/she mean DisplayLink when they say "DeviceLink" ?)
"I upgraded to macOS 14.5 today and almost expected DeviceLink to not work. Sure enough it didn't after I finished the update.
I uninstalled DeviceLink from Apps and reinstalled it again, rebooted and it still didn't see my two HP displays.
I shut down my MacBook and unplugged my USB-C Dock. I rebooted my MacBook and plugged the power to the Dual Display USB-C Dock and opened Device Link, only to notice I needed to re-install the extension again (found under Support tab). I rebooted again.
This must have reset preferences, Because I had to manually start DeviceLink from Applications and then manually reselect "Launch automatically after login".
This seemed to work and I am now back up and running with macOS 14.5 and Device Link Manager 1.10.1(Build 93) with two hp Z24n G2 displays."
Anyway, seems like a major issue. I will hold off the upgrade.