Different queries from LINQ in table with discriminator when migrating to .NET 5

I migrated our solution from .NET Core 3.1 to .NET 5. Now I am facing this issue : I have a Link model which has discriminator column with two types of values, now the LINQ to this table is not working and when I convert it to sql query and compare with previous version , these are two different queries and the .NET 5 one gave me error when I run it in PostgreSQL.

var test = _identityContext.Links.AsQueryable();

These are two different queries I get in two different versions :

In .Net Core 3.1 :

SELECT l."Id", l."Discriminator", l."Inserted", l."UserId", l.xmin
FROM "Links" AS l
WHERE l."Discriminator" IN ('GamecenterLinkModel', 'GooglePlayLinkModel')

In .Net 5:

SELECT l."Id", l."Inserted", l."UserId", l.xmin, CASE
    WHEN (g0."Id" IS NOT NULL) THEN 'GooglePlayLinkModel'
    WHEN (g."Id" IS NOT NULL) THEN 'GamecenterLinkModel'
END AS "Discriminator"
FROM "Links" AS l
LEFT JOIN "GamecenterLinks" AS g ON l."Id" = g."Id"
LEFT JOIN "GooglePlayLinks" AS g0 ON l."Id" = g0."Id"

Is something has changed in defining the discriminator in .NET 5 ?

This is My Link Model :

 [Table("Links")]
 public abstract class LinkModel : ILinkModel, ITimeStampInserted
    {
        public string Id { get; set; }

        public UserModel User { get; set; }

        public DateTime Inserted { get; set; }

        public abstract ILink ToLink();
    }

 [Table("GamecenterLinks")]
    public class GamecenterLinkModel : LinkModel
    {
        public override ILink ToLink()
        {
            return new GameCenterLink(Id);
        }
    }

 [Table("GooglePlayLinks")]
    public class GooglePlayLinkModel : LinkModel
    {
        public override ILink ToLink()
        {
            return new GooglePlayLink(Id);
        }
    }

My IdentityContext class :

  public class IdentityContext : DbContextBase
  {
    public DbSet<UserModel> Users { get; set; }

    public DbSet<RefreshTokenModel> RefreshTokenLinks { get; set; }

    public DbSet<GamecenterLinkModel> GamecenterLinks { get; set; }

    public DbSet<GooglePlayLinkModel> GooglePlayLinks { get; set; }

    public DbSet<LinkConflictModel> LinkConflicts { get; set; }

    public DbSet<LinkModel> Links { get; set; }
  
    public IdentityContext(DbContextOptions<IdentityContext> options) : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<UserModel>().UseXminAsConcurrencyToken();
        modelBuilder.Entity<RefreshTokenModel>().UseXminAsConcurrencyToken();
        modelBuilder.Entity<GamecenterLinkModel>().UseXminAsConcurrencyToken();
        modelBuilder.Entity<LinkModel>().UseXminAsConcurrencyToken();
    }
}

UPDATE : I downgraded the EF version,Npgsql and Npgsql.EntityFrameworkCore.PostgreSQL to 3.1.3 and things work fine now, so guess it is EF upgrade issue.

UPDATE 2: I removed the [Table("GamecenterLinks")] and [Table("GooglePlayLinks")] annotation from top of the two derived classes and it solved the issue, think when I updated EF Core, it confused it with Table-Per-type and assumed they are two different table for each derived class.