netplan config is ignored, who reconfigures my network?

I have a machine with multiple NIC, for the sake of simplicity we call them

• ext0: uses DHCP, goes to the outside
• int0 and int1: have static IP adresses, go to some private network, where there is also a DHCP server running, which other machines should use.

I have only one netplan config file (/etc/netplan/01-netcfg.yaml), which reads:

network:  renderer: networkd  version: 2  ethernets:    ext0:      dhcp4: true    int0:      dhcp4: false      dhcp6: false      addresses:        - 192.168.X.X/24    int1:      dhcp4: false      dhcp6: false      addresses:        - 192.168.X.X/24

I can run netplan apply and everything works fine. After some time, however int0 and int1 get additional IPs over DHCP, although this is explicitly prohibited in my netplan config.I would not really mind that, if not additionally at some point, the default route would be transferred to one of the internal network interfaces.

Why is this happening? Which service is interferring with my network config?This is on a clean install of ubuntu 22.04.