When switching from EF Core 5 to version 8, the following problem was revealed.

If I do it first:

var task = await _context.Tasks
    .Include(t => t.Document)
    .ThenInclude(t => t.RouteStepValues)
    .FirstOrDefaultAsync(t => t.Id == taskId);

And in the future, I will execute this request with the same DocumentId that was received earlier with task:

var document = await _context.Documents
    .Include(d => d.RouteStepValues)
    .FirstOrDefaultAsync(d => d.Id == documentId);

When further trying to get the RouteStepValue from the document, it does not find the values. In the .net 5 version, this did not cause problems, and similar entities were combined.