Why when the 110 value is set, doesn't the `get_history` see 100 as the deleted value?

model.py

def price_logger(mapper, connection, target):
    data = target.__dict__.copy()
    print('Update event caught')
    print("Current Value:", data["retail"])  # Current value (working as expected)
    value = get_history(target, 'retail')
    print(f'Old value was {value}, new is {data["retail"]}')
    print('-'*10)

class History(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    gtin = db.Column(db.String(15), nullable=False)
    retail = db.Column(db.Integer)
    created = db.Column(db.DateTime, default=datetime.utcnow)

    event.listen(Item, 'after_update', price_logger)

    def __init__(self, gtin, retail):
        self.gtin = gtin
        self.retail = retail

    def __repr__(self):
        return f"{self.gtin} : {self.retail} : {self.created}"

output.txt

Update event caught
Current Value: 44
Old value was History(added=(), unchanged=[44], deleted=()), new is 44
----------
.Update event caught
Current Value: 100
Old value was History(added=[100], unchanged=(), deleted=[44]), new is 100
----------
Update event caught
Current Value: 110
Old value was History(added=[110], unchanged=(), deleted=()), new is 110

test.py

    db.session.add(Item(**example_item))
    db.session.commit()
    
    item = Item.query.first()
    item.retail = 100 
    db.session.commit()

    item.retail = 110
    db.session.commit()