Is the statement: "These people have no shame, and the neighbors should complain about them, and if they want to listen to music, they should put headphones in their ears" considered backbiting when said about non-Muslim workers who are playing loud music near homes?

If the aforementioned workers are Muslims and openly commit sins, then there is no sin upon the speaker for describing them as shameless, because they do not dislike having their actions spoken about; rather, they rejoice in them. Therefore, it is permissible to mention what an openly wicked person publicizes of his wickedness. However, if they are disbelievers, then the ruling on backbiting a disbeliever applies to them. The affected neighbors have the right to file a complaint with the competent authorities to remove the harm, in accordance with the principle "harm is to be removed" and the Hadith "There should be no harm nor reciprocating harm."