I think the easiest from a logical and efficiency point of view is using the queryset’s exists() function, documented here:
https://docs.djangoproject.com/en/stable/ref/models/querysets/#django.db.models.query.QuerySet.exists
So in your example above I would simply write:
if User.objects.filter(email = cleaned_info['username']).exists():
# at least one object satisfying query exists
else:
# no object satisfying query exists