packages.config

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Microsoft.Bcl.AsyncInterfaces" version="5.0.0" targetFramework="net48" />
  <package id="Microsoft.CSharp" version="4.7.0" targetFramework="net48" />
  <package id="Microsoft.Extensions.DependencyInjection.Abstractions" version="2.0.0" targetFramework="net48" />
  <package id="MiniProfiler" version="4.2.22" targetFramework="net48" />
  <package id="MiniProfiler.Shared" version="4.2.22" targetFramework="net48" />
  <package id="Newtonsoft.Json" version="10.0.3" targetFramework="net48" />
  <package id="Npgsql" version="4.1.11" targetFramework="net48" />
  <package id="ServiceStack" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.Client" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.Common" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.Interfaces" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.OrmLite" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.OrmLite.PostgreSQL" version="6.2.0" targetFramework="net48" />
  <package id="ServiceStack.Text" version="6.2.0" targetFramework="net48" />
  <package id="System.Buffers" version="4.5.1" targetFramework="net48" />
  <package id="System.Diagnostics.DiagnosticSource" version="6.0.0" targetFramework="net48" />
  <package id="System.Memory" version="4.5.4" targetFramework="net48" />
  <package id="System.Numerics.Vectors" version="4.5.0" targetFramework="net48" />
  <package id="System.Runtime.CompilerServices.Unsafe" version="6.0.0" targetFramework="net48" />
  <package id="System.Text.Encodings.Web" version="4.6.0" targetFramework="net48" />
  <package id="System.Text.Json" version="4.6.0" targetFramework="net48" />
  <package id="System.Threading.Tasks.Extensions" version="4.5.4" targetFramework="net48" />
  <package id="System.ValueTuple" version="4.5.0" targetFramework="net48" />
  <package id="xunit" version="2.4.2" targetFramework="net48" />
  <package id="xunit.abstractions" version="2.0.3" targetFramework="net48" />
  <package id="xunit.analyzers" version="1.0.0" targetFramework="net48" />
  <package id="xunit.assert" version="2.4.2" targetFramework="net48" />
  <package id="xunit.core" version="2.4.2" targetFramework="net48" />
  <package id="xunit.extensibility.core" version="2.4.2" targetFramework="net48" />
  <package id="xunit.extensibility.execution" version="2.4.2" targetFramework="net48" />
</packages>

TestIssueWithProfiledOrmLite.cs

using System.Data.Common;
using System.Threading.Tasks;
using ServiceStack.OrmLite;
using StackExchange.Profiling;
using StackExchange.Profiling.Data;
using Xunit;

public class OrmLiteWithConnectionFactory
{
    [Fact]
    public async Task Test()
    {
        var connectionFactory = CreateConnectionFactoryFactory();

        using (var db = connectionFactory.OpenDbConnection())
        {
            var query = "select @category as Category";

            var d = (await db.SelectAsync<Result>(query, new { category = "some text"}))
                .ToArray();

            Assert.NotEmpty(d);
            Assert.Equal("some text", d[0].Category);

        }
    }

    private static OrmLiteConnectionFactory CreateConnectionFactoryFactory()
    {
        string sqlConnectionString =
            "Server=localhost;Port=5432;User Id=postgres;Database=postgres";
        return new OrmLiteConnectionFactory(sqlConnectionString, PostgreSqlDialect.Provider)
        {   
            ConnectionFilter = connection =>
            {
                // This forces a specific datestyle when communicating with PGSQL, and ensures that we
                // use our datetime format even if the database has a separate format.
                connection.ExecuteNonQuery(@"SET datestyle TO ""ISO, DMY""");
                return new ProfiledDbConnection((DbConnection) connection, MiniProfiler.Current);
            }
        };
    }
    
    public class Result
    {
        public string Category { get; set; }
    }
}