Found a solution for ASP.NET Core to download CSV's as UTF8 with POM:
byte[] csvBytes = Encoding.Default.GetBytes(csvString);UTF8Encoding utf8 = new UTF8Encoding(true);byte[] bom = utf8.GetPreamble();var result = bom.Concat(csvBytes).ToArray();return new FileContentResult(result, MediaTypeHeaderValue.Parse("text/csv; charset=utf-8"));Excel is recognizes the downloaded CSV file than as UTF8.
