Well I fundamentally disagree with you.

Information that is put out in the open can not be expected to have any restrictions, specially those imposed by human laws.

Lack of attribution  is a social problem, paid with reputational loss if clear.

Copyright and intellectual property are just ridiculous concepts the men with guns incentivize us to use for our petty battles. All that exists are trade secrets. Either something is a secret, or it is public knowledge. There is no in-between.

It would be a different case if copilot was feeding from code that users meant to keep secret.