Entity Framework Core - 'There are multiple relationships between X and Y without configured foreign key properties.', but they are configured?

I have three entities Card, User and Category.

A card can have a category and a user (the owner of the card).

I have used FluentAPI to tell Entity Framework the relations between the entities, however I get this error

There are multiple relationships between 'Card' and 'User' without configured foreign key properties.

when they are configured.

User

public class User
{
    public int Id { get; set; }

    [Required]
    [MaxLength(MaxNameLength)]
    public string FirstName { get; set; }

    [Required]
    [MaxLength(MaxNameLength)]
    public string LastName { get; set; }

    [Required]
    [MaxLength(MaxNameLength)]
    public string Username { get; set; }

    public int Age { get; set; }

    [Required]
    public string ProfileImageUrl { get; set; }

    public IEnumerable<Card> OwnedCards { get; set; } = new List<Card>();

    public IEnumerable<Card> CurrentlySellingCards { get; set; } = new List<Card>();

    public IEnumerable<Card> SoldCards { get; set; } = new List<Card>();

    public IEnumerable<Card> BoughtCards { get; set; } = new List<Card>();
}

Card

public class Card
{
    public int Id { get; set; }

    [Required]
    [MaxLength(MaxTitleLength)]
    public string Title { get; set; }

    [Required]
    public string ImageUrl { get; set; }

    public CardTypes CardType { get; set; }

    [Column("OwnerId")]
    public int UserId { get; set; }

    public User User { get; set; }

    public int CategoryId { get; set; }

    public Category Category { get; set; }
}

Category

public class Category
{
    public int Id { get; set; }

    [Required]
    public string Name { get; set; }

    public IEnumerable<Card> Cards { get; set; } = new List<Card>();
}

FluentAPI:

protected override void OnModelCreating(ModelBuilder builder)
{
        builder
            .Entity<Card>()
            .HasOne(c => c.Category)
            .WithMany(c => c.Cards)
            .HasForeignKey(c => c.CategoryId)
            .OnDelete(DeleteBehavior.Restrict);

        builder
            .Entity<Card>()
            .HasOne(c => c.User)
            .WithMany(u => u.OwnedCards)
            .HasForeignKey(c => c.UserId)
            .OnDelete(DeleteBehavior.Restrict);

        base.OnModelCreating(builder);
}