Django Count and Sum annotations interfere with each other

While constructing a complexe QuerySet with several annotations, I ran into an issue that I could reproduce with the following simple setup.

Here are the models:

class Player(models.Model):
    name = models.CharField(max_length=200)

class Unit(models.Model):
    player = models.ForeignKey(Player, on_delete=models.CASCADE,
                               related_name='unit_set')
    rarity = models.IntegerField()

class Weapon(models.Model):
    unit = models.ForeignKey(Unit, on_delete=models.CASCADE,
                             related_name='weapon_set')

With my test database, I obtain the following (correct) results:

Player.objects.annotate(weapon_count=Count('unit_set__weapon_set'))

[{'id': 1, 'name': 'James', 'weapon_count': 23},
 {'id': 2, 'name': 'Max', 'weapon_count': 41},
 {'id': 3, 'name': 'Bob', 'weapon_count': 26}]


Player.objects.annotate(rarity_sum=Sum('unit_set__rarity'))

[{'id': 1, 'name': 'James', 'rarity_sum': 42},
 {'id': 2, 'name': 'Max', 'rarity_sum': 89},
 {'id': 3, 'name': 'Bob', 'rarity_sum': 67}]

If I now combine both annotations in the same QuerySet, I obtain a different (inaccurate) results:

Player.objects.annotate(
    weapon_count=Count('unit_set__weapon_set', distinct=True),
    rarity_sum=Sum('unit_set__rarity'))

[{'id': 1, 'name': 'James', 'weapon_count': 23, 'rarity_sum': 99},
 {'id': 2, 'name': 'Max', 'weapon_count': 41, 'rarity_sum': 183},
 {'id': 3, 'name': 'Bob', 'weapon_count': 26, 'rarity_sum': 113}]

Notice how rarity_sum have now different values than before. Removing distinct=True does not affect the result. I also tried to use the DistinctSum function from this answer, in which case all rarity_sum are set to 18 (also inaccurate).

Why is this? How can I combine both annotations in the same QuerySet?

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