This is not how totalitarian regimes are created at all. Commissars in the USSR having the power to ban books meant repercussions from the state for reading or distributing those books, and was a clear signal that similar works would meet a similar fate.
The publisher deciding to no longer sell some part of their work is entirely different. It makes no difference to your ability to enjoy a copy you own or to sell it to someone else. Nor does it affect your ability to create a similar illustrated children's book including whatever stereotypes you desire. No one is 'banning' you from doing this, although it might diminish their opinion of you.
This is not how totalitarian regimes were created in the past.
Once expressions of ideas are effectively banned, you are in a totalitarian, oppressive regime. It doesn't matter whether that banning was done by the state or by huge monopolistic corporations: the end result is the same.
Also, in this case, while corporations are leading the way, we also see increasingly loud calls for our government to step in and criminalize some forms of speech, for example those deemed "hate speech": https://www.nytimes.com/2020/10/13/magazine/free-speech.html
This is really a two-pronged attack on free speech and the free exchange of ideas: in the private sphere, individuals and companies move to effectively ban certain expressions, such as the publication of "objectionable" books. In the public sphere, there are moves to criminalize "objectionable" expressions.
The actions in each sphere reciprocally support each other, and normalize the idea that the free exchange of ideas must be policed and restricted.
The publisher deciding to no longer sell some part of their work is entirely different. It makes no difference to your ability to enjoy a copy you own or to sell it to someone else. Nor does it affect your ability to create a similar illustrated children's book including whatever stereotypes you desire. No one is 'banning' you from doing this, although it might diminish their opinion of you.