A request header field is too long for cookies generated by STS

Question

I have an external IdP, where I am not in control of the number of groups/roles. (Azure AD) And the header "Cookie" that is generated by STS (Ws Fed) exceeds the limit.

"Bad Request - Header Field Too Long HTTP Error 400. A request header field is too long."

System: .NET6 Web App+ IIS 6

Already tried:

• added <system.web><httpRuntime maxRequestLength="16777210" maxRequestHeadersTotalSize="131068"/></system.web> to web.config

• added to web.config

<security>
  <requestFiltering>
    <requestLimits maxAllowedContentLength="16777210">
      <headerLimits>
        <add header="Cookie" sizeLimit="131068" />
      </headerLimits>
     </requestLimits>
  </requestFiltering>
</security>       

• defined MaxFieldLength and MaxRequestBytes (Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters)

• added

builder.Services.Configure<IISServerOptions>(options =>
{
  options.MaxRequestBodySize = int.MaxValue;
  options.MaxRequestBodyBufferSize = int.MaxValue;
});

I was able to make it work on Kestrel: kestrelOptions.Limits.MaxRequestHeadersTotalSize = int.MaxValue, but I need to make it work with IIS.