You didn't turn on symmetry in Blender's Modeling or Sculpting! This hidden solution is in seconds.

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I was here, happily modeling my strange little bird, and suddenly I realized that its beak was crooked. It was, in fact, a fairly common mistake: at some point, I hadn't activated symmetry on the X axis, which is the one usually used to model symmetrical characters or figures.

Symmetry problems are easy to spot. If, for example, you set the top view to 7, you can clearly see if your model is crooked or has a skewed part, and if you look from below (Ctrl + 7), it is also crooked.

Correcting the symmetry problem

How do we fix this? Because doing it manually is practically impossible... unless you're a computer with legs.

The solution is very simple:

1. Go to edit mode.
2. Select the entire mesh.
3. Press F3, type "Symmetry," and press Enter.

And that's it! That should be pretty much it.

If you now go back to sculpting mode (which was my case) or modeling mode, you'll see that there are details that need to be corrected, of course. Symmetry has been applied, and I've probably changed the model a bit on both sides to make them the same, but this can be easily fixed with a little manual tweaking.

In my case, since I'm using the mouse, I can't model as precisely, but I've already corrected the edge of the beak a bit, for example.