Understanding breastmilk changes

Carolina • Mom to the perfect little girl 💕, due with #2 in October 💚

My LO is 11 weeks and I mostly pump, but we do boobie time at least once a day most days; I’ve always noticed that when I store my milk in the fridge and it separates, it’s mostly watery, about 70-80% and small fatty part on the top. This week I’ve noticed that is less watery and more fatty, I haven’t changed my diet and I don’t think either my LO or myself were sick. Any guesses/reason why I’m seeing this change??