Ubuntu continuing to try to push their snowflakes. nmcli/nmtui works acceptably well. ifupdown-ng works great. What problem is Ubuntu trying to solve?
They're trying for lock-in and failing.
Linux networking has been a solved problem since just about forever, and all this instability will do is cause people to abandon Ubuntu in favor of something less fickle.
Imagine looking for a Java solution and the only response you find is in Kotlin... fucking annoying as I have to learn Kotlin to convert it to Java... The same thing with network configuration, you're looking for something that works on Debian and you only find a Ubuntu solution....
Creating artificial lock-in that doesn't work is a double-barrel footgun blast.
The Ubuntu people are like the SystemD people: they just want to reinvent things from scratch and shove it down everyone's throats without any consideration.
You only think ifupdown-ng, nmcli/nmtui work well because you don't remember how hard it was to learn and developed scar tissue from using them. To my scar tissue, Debian/Ubuntu is well organized and tools like netplan clicked very fast and make network configuration much easier.
Guessing, but I think it probably has more to do with the various tools and frontends (GUI, cloud-init, etc.) designed to manage the configurations than it has to do with the capabilities of what the configuration system will support. I have been bitten by some of this too, but the various script hooks are still there, and I've been able to support everything else via those mechanisms.