Sup, I'm one of those old school furfags that have been around since before "furfag" was even coined, let alone moved through the entire reclamation/villainization cycle twice.
You are correct: cartoon animals, while still categorized as "ferals" by furries are also anthropomorphic.
"Feral" is not a claim about a character's mental emotional or communication abilities. It's a claim about whether a human having sex with them would "look like" having sex with a costume alien, or look like having sex with a recognizable animal. Because "feral" is first and foremost a genre of fucking porn that then expanded out to include non-erotic uses.
This relates to older obscenity laws where drawing "bestiality" was more obscene than drawing "cartoons" and so ferals had to be restricted to more high security spaces like login-walled hidden forum boards, or invitation-only clubs before the internet.
However, the act of giving an otherwise totally normal animal any human characteristic, absolutely including facial expressions and body language is anthropomorphization.
That's just. What the word means.
However, there has been a huge pushback in the last 10 years or so to the openly queer and sex positive culture of furries. They have their own sex negative movements, just like other fandoms have "antishippers" and "think of the children."
And that means washing your hands of anything that includes a dirty nasty sex word like "feral."
So now people who are deeply entrenched in a fascistic antisex narrative in broader culture are coming in to furry spaces, finding out that "ferals are when it looks like sex with an animal" and concluding that's Basically Really Zoophilic Rape Apologia.
As a result, they needed to narrow and close the definition of the Good And Wholesome, Pure Hearted Anthros to create a clear delineation from Bad Nasty Hypersexual Ferals.
And they did this by deciding that "anthro" does not mean "animal with human features," it means "animal with a bipedal, humanoid limb map."
This is gibbering nonsense, of course. First of all, anthro already has a meaning in greater society, and that meaning is also the one used by furries for the entirety of our existence, and some sex-hating newbies rolled up to start swatting us with newspapers and redefine our words in insane ways, then somehow make it look like we did that so we get the blame too.
Like, the amount of non-furries I've seen who laugh and laugh about how "furries don't even know what anthropomorphic means" is exhausting. (Hint: it tends to come from spec-fic fans who are used to distinguishing between humanoid and nonhumanoid aliens and monsters)