//Loginpartial sin cambiar
@using Microsoft.AspNetCore.Identity
//simplemente si os fijáis cambio ese dato
@inject SignInManager<IdentityUser> SignInManager
@inject UserManager<IdentityUser> UserManager

@if (SignInManager.IsSignedIn(User))
{
    <form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Index", "Home", new { area = "" })" method="post" id="logoutForm" class="navbar-right">
        <ul class="nav navbar-nav navbar-right">
            <li>
                <a asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @UserManager.GetUserName(User)!</a>
            </li>
            <li>
                <button type="submit" class="btn btn-link navbar-btn navbar-link">Logout</button>
            </li>
        </ul>
    </form>
}
else
{
    <ul class="nav navbar-nav navbar-right">
        <li><a asp-area="Identity" asp-page="/Account/Register" class="nav-link">Register</a></li>
        <li><a asp-area="Identity" asp-page="/Account/Login" class="nav-link">Login</a></li>
    </ul>
}
//loginpartial cambiado este es el que funciona
@using Microsoft.AspNetCore.Identity
@using Domotica_mysql.Data.CustomIdentity

@inject SignInManager<ApplicationUser> SignInManager
@inject UserManager<ApplicationUser> UserManager

@if (SignInManager.IsSignedIn(User))
{
    <form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Index", "Home", new { area = "" })" method="post" id="logoutForm" class="navbar-right">
        <ul class="nav navbar-nav navbar-right">
            <li>
                <a asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage">Hello @UserManager.GetUserName(User)!</a>
            </li>
            <li>
                <button type="submit" class="btn btn-link navbar-btn navbar-link">Logout</button>
            </li>
        </ul>
    </form>
}
else
{
    <ul class="nav navbar-nav navbar-right">
        <li><a asp-area="Identity" asp-page="/Account/Register" class="nav-link">Register</a></li>
        <li><a asp-area="Identity" asp-page="/Account/Login" class="nav-link">Login</a></li>
    </ul>
}