If you want to serve the soup a little finer, replace the stale white bread with (not too few) crispy croutons and the eggs are not whisked, but poached in the soup. This is also possible without vinegar, (possibly in a ladle) only the egg yolk is then exposed and is not surrounded by the egg white. One egg per person for this preparation.
I prefer meat or poultry broth for this recipe. But if you want to prepare the recipe vegetarian, you can also use vegetable broth and then leave out bacon or ham.