removing VLAN= from .network file and restarting systemd-networkd doesn't remove vlan from interface

[OtherSystems]

systemd version the issue has been seen with

239-5

Used distribution

debian sid

Expected behaviour you didn't see

when removing the VLAN= line from a .network file, that the vlan gets removed from that interface.

Unexpected behaviour you saw

when removing the VLAN= line from the .network file for an interface, the vlan device did not get removed from the interface when restarting systemd-networkd

Steps to reproduce the problem
create a vlan in a .netdev file
add vlan to an interface by adding a VLAN= line its .network file
restart systemd-networkd
see vlan being added to the interface (ip link show)
remove VLAN= line from .network file of the interface
restart systemd-networkd
observe the vlan still being present on the interface (ip link show)

[ghost]

The manual page of systemd-networkd says

This also means that when configuration is updated and systemd-networkd is restarted, netdev interfaces for which configuration was removed will not be dropped, and may need to be cleaned up manually.

I think what you reported is exactly the documented behavior.

[OtherSystems]

You are correct. Initially it seemed unintuitive, but I can see the value of leaving manually configured stuff on it's own.

Sorry about that :)