>They lengthened the plane without redesigning the rest of the components to compensate.

Not exactly. It's the placement of the newer, larger engines that's largely responsible for the different handling characteristics.

>This changed fundamental aerodynamics on how it flies.

Yes.

>The plane is dynamically unstable.

No, it just has different handling characteristics in some parts of the flight envelope.

Dynamically unstable means that it will leave controlled flight if it does not receive control input, and that the departure from controlled flight will accelerate after it starts, therefore requiring constant computer-assisted control inputs. Pretty sure this is not the case, but it will have different and potentially dangerous behaviors for some speeds, angles of attack and thrust settings.

That's literally what happens to the 737 max airframe. Specifically, the angle of attack is prone to increasing at high angle of attacks.

That's not dynamic instability.

Are you going to provide any source for that?

http://nymag.com/intelligencer/2019/03/is-the-boeing-737-max...

If (as appears to be the case) you regard any random person on the internet as a source, then sure:

https://www.quora.com/Are-any-commercial-airliners-other-tha...

The sources I linked to:

http://nymag.com/intelligencer/2019/03/is-the-boeing-737-max...

https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-...

These are international, reputable organizations unlike a Quora thread. That would be like me using reddit as a primary source. Get real. I am going to believe the reputable news sources, over random people on the Internet.

And two can play at that game:

https://www.quora.com/How-long-do-you-think-it-will-be-befor...

https://www.quora.com/Should-divergent-instability-be-allowe...

Can you actually get a 737 MAX in controlled flight, into a state where its angle of attack will keep increasing faster and faster without changing the control inputs, until it stalls? That would be dynamic instability, albeit only during certain situations.