Girls, one more question. I don't understand what's happening. One day…

Girls, one more question. I don't understand what's happening. One day the baby takes the breast well and has no problems all night, sleeps well. One day she sucks poorly from the breast and fusses on it, but doesn't cry or refuse it, just like she can't suck normally, but wants to eat. What is this? It mostly happens at night. I change her position as soon as I don't hold her and try different positions, but nothing helps with such a thing, although I always apply them in the same way. If she sucks poorly, then I know that almost every hour she will wake up ?‍♀️It wasn't like that with my older child. What could it be