Seed Vault is probably the GB that scales the worst. You have to level it to around 20 to double its production.For what it's worth, the double collection can also work with wishing wells (and their counterparts). So while extremely slight odds, this is going to become the 3rd GB that can 'produce' diamonds, behind the Chateau (via quest rewards) and Seed Vault (directly).
Anyway, just going to repeat that, much like the Kraken, this GB isn't designed to be impactful until well beyond level 10. New GBs are no longer designed to scale well until level 10, then slowly afterward anymore. Inno caught on that GBs are very commonly levelled well past that point and have adjusted the bonus scaling accordingly. Myself, I don't consider the Kraken to start being worthwhile until around level 50 when the activation chance approaches 90%. At level 10 and only 32%, that's pretty bad. The Blue Galaxy is really no different.