“Regulators invited public comment on whether the US broadcast license for Fox Corp.’s TV station in Philadelphia should be renewed after a grassroots organization asked that it be denied, saying Fox knowingly broadcast false news about the 2020 election.”
There are no special regulations on what constitutes a “news” broadcast in the US.
If you lie in public, whether on TV or Facebook, you can be sued for defamation. Which is exactly what happened to Fox.
In specific circumstances, you can be prosecuted for criminal libel but those circumstances do not apply to Fox.