Ubuntu 20.04 Netplan Static Configuration Gets Reset After a While

Expected behavior:

My netplan configuration is always used and the static IP addresses I configured stay like configured.

Actual behavior:

Somehow the machine "forgets" the configuration and acquires different IP addresses via DHCP.

Netplan config:

"/etc/netplan/00-installer-config.yaml"

network:
  renderer: networkd
  version: 2
  ethernets:
    enp1s0:
      dhcp4: false
      addresses:
        - 192.168.0.11/24
    enp3s0:
      dhcp4: false
      addresses:
        - 192.168.1.11/24
      gateway4: 192.168.1.1
      nameservers:
        addresses:
          - 192.168.1.1
    enp4s0:
      dhcp4: false
      addresses:
        - 192.168.2.11/24

Where does this behavior come from? Thanks in advance for any help.