A cover of a song can potentially be considered copyright infringement if the necessary permissions and licenses have not been obtained from the copyright owner. When creating a cover song, the artist is essentially creating a new recording of an existing copyrighted musical composition, including the melody and lyrics. In order to legally produce, distribute, or perform a cover song, the artist must obtain the appropriate licenses from the copyright owner. Failure to do so can result in legal consequences, including fines and legal fees. However, if the necessary permissions and licenses have been obtained, a cover song can be perfectly legal and even encouraged in most countries, including the United States. It is important for artists to understand the legal requirements for using copyrighted material in their work in order to avoid potential legal issues.
Also worth reading: "Is it possible to use clip art for a logo design without risking legal action or copyright infringement?" · How can I legally give credit to an artist on Etsy for inspiration, while avoiding copyright infringement, when creating similar but non-identical work? · "Is it considerable as copyright infringement if I edit and use a copyrighted image from the internet after making changes to it?"