> It was close to entering the public domain in the U.S. several times: each time, copyright protection was extended. It could have entered the public domain in four different years: first in 1955, renewed to 1986, then to 2003 by the Copyright Act of 1976, and then to 2023 by the Copyright Term Extension Act (also known pejoratively as the “Mickey Mouse Protection Act”) of 1998. It has been claimed that these extensions were a response by Congress to extensive lobbying by The Walt Disney Company.
This undos nothing. We just limit damage to what has already been done for this one film. there are other things still in copyright that wouldn't have been, and that damage is still being done, and will until that copyright expires.