Only up to 2000. It’s unclear if the catalog from 2000 to 2025 will be fully made open. There may be legal obstacles if the originating authors and institutions don’t consent.
I haven’t been able to find anything that states otherwise. What changes in January is the policy for new publications.
What's different legally about the publications prior to 2000?
Everything is going to be open, they have been saying this for ages. The issue isnt rights, they have those, its been funding this.