Comment 1 for bug 1975750

According to https://bugs.launchpad.net/netplan/+bug/1756590 it is indeed seems to be deprecated.

We generate netplan config in src/maasserver/preseed_network.py and we need to update it so it is using new syntax.

It is mentioned that
> if somebody uses the (now deprecated) gateway4/6 fields it will still work, but print a warning.

So I would assume it is not critical, but for sure needs to be handled until it becomes unsupported.