The only one I had heard of (and probably read as a kid ) was the Mulberry street one. Some people I know remember the zoo one.
There is a reason why the people complaining constantly say how much they love the Cat in the Hat - they want you to think that's what is being "cancelled" or "banned".
I think this over issue is just being blown up by both sides into something it really is not
6 overall unpopular books (I would guess make up less than 1% of their revenue... from what most are saying only 2 of the 6 even appear to be known... I never heard of any of them)
Finally got some sources as to what is so "terrible"
After I reviewed them I will chip in they are not anywhere close to his best work
Some are VERY bad books quality wise
But really the only one I think is a major issue is the last one (Cats Quizzer)
Most of the issues is more to do with imagery than actual words
And to Think I Saw on Mulberry St
"a Chinese man who eats with sticks" [china]
If I Ran the Zoo
"helpers who wear their eyes at a slant" [china]
McElligot Pool
"some eskimo fish" [eskimo]
On Beyond Zebra
"nazzim of bazzim" [middle eastern?]
Scrambled Egg Super
"great happy gay families with cousins" [gay]
"beyond the north pole" [eskimos]
Cats Quizzer
"how old do you have to be to be japanese" [japan?]
"do japanese eat with pogo sticks or joss sticks [japan]
"are there many women kings, are there any women uncles" [sexist]
"who is taller a tall pygmy or short giant" [african pygmy]
"all japanese are japanese the moment they are born" [japan]
Cats Quizzer reads awful, it was never a good book to begin with
And certain things even I reacted to as offensive (eg Joss Sticks which are for religious purposes being used as utensils, the commentary women can't be in charge of a country, and I get why woke culture dislikes the pygmy part.
But really this book is more of a Quiz book (as title implies) with random questions and answers (and super out of date, which I attribute to some errors)
Oh and typical American lunacy; a Japanese baby is NOT Japanese the moment they are born either lol
Japan attributes nationality by blood, not location of birth (eg if you drive across border to USA and have a child, the child is an American. If you fly to Japan and have a child the child is not Japanese)