Earlier quoted context omitted.
Maybe manim should not have used MIT as the license in the first place, since the license permits it.
MIT license does not give someone license to advertise a completely different project with your project's name and the name of its famous author.
We already know they took the open-source code, re-implemented it and closed-sourced it into a product and that is permitted under the MIT license:
>> So you vibe ported manim to rust, kept it closed source, and you’re selling access to it with a monthly subscription? This isn’t satire?
This isn't the same as what you would get from something like Markdown [0], which explicitly says:
"Neither the name “Markdown” nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission."
What he must do is to attribute credit of the library to the original author (3Blue1Brown) for the derived use. But other than that, this is permitted.