Ubuntu 20.04 – Setting Default valid_lft and preferred_lft with Netplan

What's the impact, if any, on having values greater than zero/forever for valid_lft and preferred_lft? Should I worry about this, and if so, how to set it automatically to forever at boot time (preferably using Netplan)?

root:~# ip a
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether aa:00:11:22:33:44 brd ff:ff:ff:ff:ff:ff
    inet 111.111.111.111/32 scope global ens3
       valid_lft 86154sec preferred_lft 86154sec
    inet 222.222.222.222/32 scope global ens3
       valid_lft forever preferred_lft forever
    inet6 fe80::aaa:bbb:ccc:ddd/64 scope link 
       valid_lft forever preferred_lft forever

root:~# ip addr change 111.111.111.111 dev ens3 valid_lft forever preferred_lft forever

root:~# ip a
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether aa:00:11:22:33:44 brd ff:ff:ff:ff:ff:ff
    inet 111.111.111.111/32 scope global ens3
       valid_lft forever preferred_lft forever
    inet 222.222.222.222/32 scope global ens3
       valid_lft forever preferred_lft forever
    inet6 fe80::aaa:bbb:ccc:ddd/64 scope link 
       valid_lft forever preferred_lft forever

I am asking this question because I realized that the server default IP address switched from 111.111.111.111 to 222.222.222.222 without manual interraction, i.e., ifconfig -a displayed this for ens3:

root:~# ifconfig -a
ens3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 222.222.222.222  netmask 255.255.255.255  broadcast 0.0.0.0
        inet6 fe80::aaa:bbb:ccc:ddd  prefixlen 64  scopeid 0x20<link>
        ether aa:00:11:22:33:44  txqueuelen 1000  (Ethernet)
        RX packets 206473  bytes 54232020 (54.2 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 111121  bytes 19855468 (19.8 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

root:~# cat /etc/netplan/*.yaml 
network:
    version: 2
    ethernets:
        ens3:
            dhcp4: yes
            match:
                macaddress: aa:00:11:22:33:44
            mtu: 1500
            set-name: ens3
            addresses:
               - 111.111.111.111/32
               - 222.222.222.222/32
            nameservers:
                addresses:
                    - 8.8.8.8
                    - 4.4.4.4
                    - 1.1.1.1
                    - 1.0.0.1

Could valid_lft and preferred_lft be the reason of the switch?

If not, how to make sure that the main IP address remains 111.111.111.111 in this configuration? I'm using Virtualmin, and once in a while it flashes a message saying that the main IP addess has been changed to 222.222.222.222, and offers to modify it from 111.111.111.111 to 222.222.222.222. At the time, ifconfig displays 222.222.222.222 as shown above.