This is more FYI, I haven't had time to properly debug it.
Booting 5.2 causes systemd-networkd to fail to bring any interface up, it will fail with: "Could not bring up interface: Invalid argument"
However, booting 5.1.16 with the same software works just fine.
Sounds like something was changed in, what I assume is, the netlink API
This is a duplicate of bug 203769
*** This bug has been marked as a duplicate of bug 203769 ***