Adults can decide for themselves about vaccines and masks, but do they put their children in harms way of they fail to do so. If their child dies of covid should they be punished in any way for their failure to take proper safety precautions?
No, a typical parent should not be "punished in any way."
In the first place, life is FULL of "harms," not just for children, but for everyone. The possibility of "harms" exists both inside and outside one's home, just about any time one encounters another person, plant, animal, inanimate thing, even the open atmosphere.
To make someone completely safe would require a level of "security" so oppressive life would hardly be worth living.
Meanwhile, there is a lot of "scaremongering" about a disease that evidence so far shows a minimal threat (might catch a cold) to the vast majority of children. A threat that even among those who do experience infection risks only a tiny proportion to serious illness and/or death.
We also know now which members of any age in our society are at greatest risk, i.e. those who already have serious lung (breathing) issues, AND one or more OTHER co-morbidities. (Same as a typical Flu season BTW).
Now
if one could show a particular parent (single parent home), or pair of parents had a child who was at high risk and refused to take precautions, then perhaps a case could be made of abuse.
Otherwise? No, as IMO we've already gone overboard in the "child protection" ideology to a point where even "harsh words" can get a child removed from parental custody.
(Small wonder we have so many growing up to be selfish, self-centered egotists. Doubt me? Check TikTok and Twitter feeds sometime.)