The ACLU tweets, quoted in "The ACLU Suddenly Reverses Its Support For Transparency/The long-time civil liberties organization continues its partisan transformation" (Inquire).
The ACLU tweet links to this NBC News article, "They fought critical race theory. Now they’re focusing on ‘curriculum transparency.' Conservative activists want schools to post lesson plans online, but free speech advocates warn such policies could lead to more censorship in K-12 schools." From that article:
[T]eachers, their unions and free speech advocates say the proposals would excessively scrutinize daily classwork and would lead teachers to pre-emptively pull potentially contentious materials to avoid drawing criticism....
“It’s important we call this out,” said Jon Friedman, the director of free expression and education at PEN America, a nonprofit group that promotes free speech. “It’s a shift toward more neutral-sounding language, but it’s something that is potentially just as censorious.”