ASP.NET Core 7 Razor model custom validation - comparing 2 dates not working

Question

I have 2 binding fields in a Razor page as shown below:

CSHTML.CS

[BindProperty]
[Required(ErrorMessageResourceType = typeof(MsgsResource), ErrorMessageResourceName = MandatoryFld)]
[CompareDate("DateTo", ComparisonType.LessThanOrEqualTo, ErrorMessageResourceType = typeof(MsgsResource), ErrorMessageResourceName = DateFromNotOk)]
public DateTime DateFrom { get; set; }

[BindProperty]
[Required(ErrorMessageResourceType = typeof(MsgsResource), ErrorMessageResourceName = MandatoryFld)]
[CompareDate("DateFrom", ComparisonType.GreaterThanOrEqualTo, ErrorMessageResourceType = typeof(MsgsResource), ErrorMessageResourceName = DateToNotOk)]
public DateTime DateTo { get; set; }

CSHTML

<div class="mb-4">
   <div class="row">
      <div class="col-6">
         <label asp-for="DateFrom" class="form-label text-muted fw-semibold mb-3">@CommonResource.FromDate</label>
         @Html.TextBoxFor(m=> m.DateFrom, new { @class="form-control flatpickr flatpickr-input", type = "date", data_provider="flatpickr" })
         <span class="invalid-feedback" asp-validation-for="DateFrom"></span>
   </div>
   <div class="col-6">
      <label asp-for="DateTo" class="form-label text-muted fw-semibold mb-3">@CommonResource.ToDate</label>
      @Html.TextBoxFor(m=> m.DateTo, new { @class="form-control flatpickr flatpickr-input", type = "date", data_provider="flatpickr" })
      <span class="invalid-feedback" asp-validation-for="DateTo"></span>
   </div>
 </div>
</div>

Both dates default to a specific date with a difference of say 30 days apart from today.

I have this custom attribute, CompareDate, to verify the following in both server and client-side:

1. DateFrom is >= DateTo
2. DateTo is <= DateFrom

During a Ajax call to retrieve records on a OnPost method, model validations will be triggered. The first check will fail because DateTo has a value of DateTime.MinValue (not its default value). On the 2nd validation check, both DateFrom and DateTo are as per their default values and hence the validation is ok.

I just wonder why DateTo is set to DateTime.MinValue even though it has a default value in the first check. Seems like I can only set the CompareDate validation on DateTo only.

Please advise. Thanks.