ASP.NET Basic search form returns += in the url but just needs to return =

Question

I'm working on a tutorial for ASP.Net and in the tutorial we are building a basic search form to search a list. When I am running the code, if I type a string or character into the search bar, I don't get any results. I figured out that if I go to the URL it says .../Restaurants/List?searchTerm=+Ja, If I change the url to say .../Restaurants/List?searchTerm=Ja it successfully searches the term. (I searched "Ja"). I'm wondering why it adds the + and how to make it so it doesn't add that, so it successfully searches the wanted term. Check out some code below.

list.cshtml.cs:

... ...

     public class ListModel : PageModel
    {
        private readonly IConfiguration config;
        private readonly IRestaurantData restaurantData;

        public string Message { get; set; }
        public IEnumerable<Restaurant> Restaurants { get; set; }
        public ListModel(IConfiguration config, IRestaurantData restaurantData)
        {
            this.config = config;
            this.restaurantData = restaurantData;
        }
        public void OnGet(string searchTerm)
        {
            Message = config["Message"];
            Restaurants = restaurantData.GetRestaurantsByName(searchTerm);
        }
    }
}

list.cs.html:

    @page
@model ListModel
@{
}

<h1>Restaurants</h1>

<form method="get">
    <div class="form-group">
        <div class="input-group">
            <input type="search" class="form-control" value=" " name="searchTerm">
            <span class="input-group-btn">
                <button class="btn btn-default">
                    Search
                </button>
            </span>
        </div>
    </div>
</form>
 <table class="table">
     @foreach(var restaurant in Model.Restaurants)
     {
     <tr>
         <td>@restaurant.Name</td>
         <td>@restaurant.Location</td>
         <td>@restaurant.Cuisine</td>
     </tr>
     }
 </table>



<div>@Model.Message</div>