What are the white spots in open wound due to necrosis after breast lift/augmentation? (Photo)

Those can be normal areas of fibrinous exudate and can be a normal part of healing. Follow up with your plastic surgeon once a week to follow the healing process. Keep the area clean with soap and water and keep ointment on it like neosporin or aquaphor. Some collagenase can help soften up the fibrinous layer. Make sure you are eating plenty of calories, particularly protein like dairy, eggs, fish, meat, etc... Hang in there! This will heal eventually.

Thank you for your question about your wound. I
strongly urge you to speak directly with the plastic surgeon who performed your
procedure. I agree with my colleagues that this is not a question for this
forum, but one for you to speak directly with your board-certified physician as soon as
possible.

This is something you should be asking your plastic surgeon and not in this forum.  This involves your post-op care and should be directed by him or her.  Good luck.