Here is another article about the bill, dating from before the revisions. The purpose of the bill is to ensure that women who abuse their bodies while pregnant, then the baby dies of issues stemming from the self-abuse, cannot be criminally prosecuted. The primary focus is on women who give birth to drug addicted babies and the baby dies of withdraw: https://californiaglobe.com/articles/infanticide-or-pregnancy-loss-abortion-bill-passes-assembly-judiciary-committee/

Here are some quotes from the article:

However, buried in his alert is the law: “Penal Code section 187 defines murder as ‘the unlawful killing of a human being, or a fetus, with malice aforethought.’ Reference to ‘a fetus’ was added in 1970 when the California Legislature amended section 187,” Bonta said. His alert “reiterates that the Legislature did not intend to include a pregnant person’s own actions that might result in a miscarriage or stillbirth.” But if the “fetus” is killed due to drug addiction and drug use by the mother, how can Bonta claim that isn’t the “intent” of the law?>

The California Family Council explains its opposition:

They intend to not only codify the killing of unborn children throughout all nine months of pregnancy but to decriminalize killing newborns days or even weeks after birth.

New language added to AB 2223 last week revealed the disturbing intent. The proposed legislation would shield a mother from civil and criminal charges for any “actions or omissions” related to her pregnancy, “including miscarriage, stillbirth, or abortion, or perinatal death.” Although definitions of “perinatal death” vary, all of them include the demise of newborns seven days or more after birth...peri-natal death is considered up to one month upon delivery. >

This is the part of the bill that was revised:

She also noted that according to AB 2223, law enforcement will be barred from investigating an infant death.>

So at least there isn't carte blanche freedom to murder any baby 30 days or younger with no fear of investigation, but still... do we really want to encourage drug addicted pregnant women to continue to use drugs?