try another way to implement the data stucture

UserService.DatabaseLayer/DataModels/UserDbSettings.cs

@@ -0,0 +1,22 @@
+using System.Collections.Generic;
+using System.Linq;
+using LinqToDB.Configuration;
+
+namespace UserService.DatabaseLayer.DataModels
+{
+    public class UserDbSettings : ILinqToDBSettings
+    {
+        public IEnumerable<IDataProviderSettings> DataProviders => Enumerable.Empty<IDataProviderSettings>();
+
+        public string DefaultConfiguration => "MySqlServer";
+        public string DefaultDataProvider => "MySqlServer";
+
+        public IEnumerable<IConnectionStringSettings> ConnectionStrings
+        {
+            get
+            {
+                yield return new ConnectionStringSettings();
+            }
+        }
+    }
+}