Exception "Property 'System.Datetime Date' is not defined for type 'System.Nullable`1[System.Datetime]' (Parameter 'Property')"

Question

I upgraded EF Core to version 3.1.6 and am getting this exception when running a test.

The methods that cause this are these two:

public static IQueryable<CashoutRequest> WhereTransferOrInstitutionTransferStartDate
(
    this IQueryable<CashoutRequest> cashoutRequests, 
    DateTime? date
)
{
    if (date == null) return cashoutRequests;

    var startDate = date.Value.Date;

    return cashoutRequests.Where(cashoutRequest => 
        cashoutRequest.Transfer.CreatedAt.Date >= startDate
        || 
        cashoutRequest.InstitutionTransfer.CreatedAt.Date >= startDate
    );
}

public static IQueryable<CashoutRequest> WhereTransferOrInstitutionTransferEndDate
(
    this IQueryable<CashoutRequest> cashoutRequests, 
    DateTime? date
)
{
    if (date == null) return cashoutRequests;

    var endDate = date.Value.Date;

    return cashoutRequests.Where(cashoutRequest => 
        cashoutRequest.Transfer.CreatedAt.Date <= endDate
        || 
        cashoutRequest.InstitutionTransfer.CreatedAt.Date <= endDate
    );
}

The fields CreatedAt are not nullables, as if the Entity Framework Core made them nullables in the execution?

Entities:

    public class CashoutRequest
        {
            public long Id { get; set; }
            public long? TransferId { get; set; }
            public DateTime CreatedAt { get; set; } = DateTime.Now;
            public DateTime? ReprovedAt { get; set; }
            public DateTime? ApprovedAt { get; set; }
            public DateTime? CanceledAt { get; set; }
            public Transfer Transfer { get; set; }
            public InstitutionTransfer InstitutionTransfer { get; set; }
}

public class Transfer
    {
        public long Id { get; set; }
        public DateTime CreatedAt { get; set; } = DateTime.Now;
        public DateTime? ApprovedAt { get; set; }
        public DateTime? CanceledAt { get; set; }
        public DateTime? ReprovedAt { get; set; }
    }

public class InstitutionTransfer
{
    public long Id { get; set; }
    public DateTime CreatedAt { get; set; } = DateTime.Now;
    public DateTime? ApprovedAt { get; set; }
    public DateTime? CanceledAt { get; set; }
    public DateTime? ReprovedAt { get; set; }
    public long? CashoutRequestId { get; set; }

    public CashoutRequest CashoutRequest { get; set; }
}