Generally, in asp.net core Razor page, we are using the <select> tag helper. So, you can try to use it, refer to the following code:

In the Country.cshtml.cs file: before returning select options list to client or ViewBag, use HttpUtility.HtmlDecode() method to decode the text and convert COTE D'IVOIRE to COTE D'IVOIRE.

    public class CountryModel : PageModel
    {
        
        public string Country { get; set; }
        public List<SelectListItem> Countries { get; set; }
        public void OnGet()
        {
            Countries = new List<SelectListItem>
            {
                new SelectListItem { Value = HttpUtility.HtmlDecode("COTE D&#x27;IVOIRE"), Text = HttpUtility.HtmlDecode("COTE D&#x27;IVOIRE") },
                new SelectListItem { Value = "Mexico", Text = "Mexico" },
                new SelectListItem { Value = "Canada", Text = "Canada" },
                new SelectListItem { Value = "USA", Text = "USA" },
                new SelectListItem { Value = "COTE D&#x27;IVOIRE", Text = "COTE D&#x27;IVOIRE" },
            };
        }
        
    }

Country.cshtml: Use the Html.Raw() method to decode the text and use foreach statement to display the options

    @page "/country"
    @model Core8Razor.Pages.CountryModel


    <select asp-for="Country" >
        @foreach(var item in Model.Countries)
        {
            <option value="@item.Value">@Html.Raw(item.Text)</option>
        }
    </select>
 
 

The result as below:

About the <formselect>, whether it is a custom tag helper (create by yourself) or a third-party component? If it is created by yourself, when display the value, you could use the above method to decode the value. If you are using third-party components, can you tell us which package you are using?