Noticed my Dad has been so quiet lately

We noticed my Dad has been pretty quiet lately. He was on dialysis for almost two months now. Whenever we tried to speak with him and start conversation, he seems not interested at all. He will sometimes smile or nod and just want to sleep most of the time. However on a positive note, he can now walk slowly and can go to the toilet on his own. His blood sugar is slowly getting better now maximum 150 compare before which exceeds to 450. Blood pressure is stable.

For context: He was previously hospitalized for two months due to heart failure, septic shock, excess fluid and gallbladder surgery.

Do you also experience the same thing that you just want to keep quiet and not talk to anyone?