I've found that a lot of people say that the tinker cat refers to the fat blue man.
But as a post-90s generation, I still want to say something.
Ding-dong cats are yellow, as follows. It is a cat that can only spell, and the recipe is "Ding-Dong Spell Change"
In fact, this cartoon is also very good.
Doraemon, when introduced to China, was translated as Little Ding-Dong, and later changed to its original name Doraemon.
It's the blue fat man we're familiar with.
Coincidentally,
Both manga are written by Fujiko F. Fujio