Why does my .Net Core application get an exception when trying to delete a database file created by DevExpress XPO?

Question

I have a .NetCore (.Net 8.0) application that uses DevExpress XPO.

The application creates and keys a backup file. I create a series of rolling backups that keeps a number of backups on disk and then deletes the oldest when the threshold is exceeded.

The application is getting "process cannot access the file" exceptions when I attempt to delete a backup file created during the current session.

Within the application, I've created a simplified snippet of code (with marking the database) which recreates the exception every time it's run.

Consider the following code snippet:

var connectionString = "XpoProvider=SQLite;Data Source=filename.db";
 _ = XpoDefault.GetConnectionProvider(connectionString, AutoCreateOption.DatabaseAndSchema);

 var backupDBFileName = @"BackupDBFile.db";

if (!File.Exists(backupDBFileName))
{
    File.Copy("filename.db", backupDBFileName);
}

var connectionString = SQLiteConnectionProvider.GetConnectionString(backupDBFileName);
var provider = XpoDefault.GetConnectionProvider(connectionString, AutoCreateOption.DatabaseAndSchema, out IDisposable[] objsToDispose);

var dictionary = new DevExpress.Xpo.Metadata.ReflectionDictionary();
var dataLayer = new ThreadSafeDataLayer(dictionary, provider);
XpoDefault.DataLayer = dataLayer;

// Dispose/Disconnect
// If there are objects that needs disposing along with the Data Layer, dispose of them
if (objsToDispose != null)
{
    foreach (var obj in objsToDispose)
    {
        obj.Dispose();
    }
}

XpoDefault.DataLayer.Dispose();
XpoDefault.DataLayer = null;

// Trying to cleanup                    
System.GC.Collect();
System.GC.WaitForPendingFinalizers();

 try
 {
     if (File.Exists(backupDBFileName))
     {
         File.Delete(backupDBFileName);
     }
 }
 catch (Exception ex) {}

When I attempt to delete the backup file [File.Delete()], I get the following exception..

The process cannot access the file 'BackupDBFile.db' because it is being used by another process.