Nested serializers strips primary key from validated_data in update method

[erdos4d]

I am trying to do a ManyToMany update with a nested serializer and when I go to set the field with the validated data, the primary keys are not there for me to form a queryset with. A simplified example of what I'm facing would be the following:

from django.db import models
from django.contrib.auth.models import AbstractUser
from rest_framework.serializers import ModelSerializer

class User(AbstractUser):
    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = []
    email = models.EmailField(blank=True, null=True)
   
class Team(models.Model):
    name = models.CharField(blank=False, null=False, max_length=120)
    users = models.ManyToManyField(to=User)

class UserSerializer(ModelSerializer):
    class Meta:
        model = User
        fields = [
            'pk',
            'first_name',
            'last_name',
            'password',
            'type',
            'username',
            'email'
        ]

class TeamSerializer(ModelSerializer):
    users = UserSerializer(many=True)

    class Meta:
        model = Team
        fields = ['pk', 'name', 'users']

    def update(self, instance, validated_data):
        user_pks = [u.get('pk') for u in validated_data.pop('users')]
        instance.name = validated_data.get('name')
        instance.users.set(User.objects.filter(pk__in=user_pks))
        instance.save()
        return instance

The update method in the team serializer is what I want to do, but when my data makes it into the validated_data object, the primary key has been removed. Is there any way to tell the framework to keep it in? Thanks for your help.