Change casing of a model's name referenced by ManyToManyField generates unnecessary migrations.

[AliGhotbizadeh]

I have models like

class DataCenter(models.Model):
    title = models.CharField(max_length=100)

class Project(models.Model):
    datacenter = models.ForeignKey('DataCenter', on_delete=models.CASCADE)

Then I have decided to rename it into "Datacenter" so I was refactored my code and call the "makemigrations" command. But no migration file has created and it was obvious because model names are lowercased in the database schema.
after a while, I have added this model

class Package(models.Model):
   datacenters = models.ManyToManyField('Datacenter')

after creating that model every time I call the "makemigrations" command, the same alter migration has been created.

migrations.AlterField(
            model_name='package',
            name='datacenters',
            field=models.ManyToManyField(related_name='packages', to='operations.Datacenter',
                                         verbose_name='datacenters'),
),

after hours of debugging, I found that in the MigrationLoader's graph, the model name is "DataCenter" because no "RenameModel" migration is even created. then in the "deconstruct" of the M2M field unlike the ForiegnKey field, the "to" attribute is set from "_meta.label" instead of "_meta.label_lower".
and that causes a false change detection in "MigrationAutodetector" every time.

[Mariusz Felisiak]

Thanks for the report, it was fixed in aa4acc164d1247c0de515c959f7b09648b57dc42 (Django 4.0+).

[Mariusz Felisiak <felisiak.mariusz@…>]

In b8f3a3a:

Refs #33119 -- Added tests for changing model name case referenced by ManyToManyField.

Fixed in aa4acc164d1247c0de515c959f7b09648b57dc42.