iroute sometimes gets lost using dco-module

Describe the bug
I have a server and a client previously running debian buster. The client is running in daemon mode and is always connected. i had a stable connection for years.
The clients network (192.168.89.0/24) is routed to the server by
a) giving it a fixed ip-adress within the vpn-subnet
b) and setting an iroute
in the client-file within the ccd-dir.

additionally the route-property (192.168.89.0/24) is set in the server.conf.

After upgrading both of them (didn't check what happens if only the server was upgraded) to bookworm using openvpn 2.6.3 and enabling the dco-module, behaviour changed as excepted:
since the dco-module is using kernel-routes (instead of the old internal routing-mechanism) i now have one route on the serverside, that is always set, if the server-daemon is running (resulting from the route-property):

192.168.89.0/24 via 192.168.23.2 dev tun0 metric 200

and one route, that is automatically beeing added if the client is connected:

192.168.89.0/24 via 192.168.23.253 dev tun0 metric 100

So far so god...

But: There is a strange behavior that seems to occur, if the client changes its public ip-address, for example through dhcp by the provider (i think, it has to do with that, but i'm not sure).

The route added by the dco-module (because of the iroute-command in client ccd) is getting lost.

ip route show

then doesn't list it anymore. The 192.168.89.0/24-network is then not reachable anymore.
But the vpn-channel seems to be alive since i can access the client through its static vpn-subnet-ip (192.168.23.253).

To Reproduce

• Setup a server using dco-module
• configure a client to route its subnet using iroute in ccd
• let a client connect and keep the connection alive until it's ip-address changes
• check kernel-routing-table on server-side

Expected behavior
The route created by the dco-module should not get lost

Version information (please complete the following information):
Server:

• OS: debian bookworm
• OpenVPN version: 2.6.3
• DCO: 0.0+git20230324-1

Client:

• OS: debian bookworm
• OpenVPN version: 2.6.3
• DCO: 0.0+git20230324-1

Additional context
I have an other client still running buster and therefore without dco enabled. this doesn't cause any problems. but it doesn't change its ip-adress. I dont know if it is related to that or if it makes a difference, when the client is using the dco-module. this just as a hint to you...

thanks for your effort and greetz,
Karsten

Reproduce the setup described with OpenVPN 2.6.3 and the DCO module: a client CCD iroute, a changing client public IP, and the server's kernel routing table. Start with ip route show on the server before and after the address change; done means the route for 192.168.89.0/24 remains present and the client subnet stays reachable.