The baby just changed into Taizi Lezhiyue 3-stage milk powder and had loose bowels. Is it indigestible?

Hello, if we can rule out the cause of the baby's illness, it is likely that the baby can't accept it for a while after suddenly changing milk powder. Is it a direct transition to new milk powder without changing milk? On the first day, 1/3 new milk powder was added to the original milk powder. After two or three days of adaptation, if the baby can accept it, the ratio will be adjusted to 1: 1 in two or three days, then the ratio of old and new milk powder will be 2: 1 in two or three days, and finally the transition to new milk powder will be completed. Changing baby's milk powder is a gradual process.