I've got an idea on how to securely handoff, or verify that that the baker from the previous bread is the baker of the new bread to eliminate this current issue.
Passphrase: Morning sun brings heat.
1) Every baker for every bread takes a known passphrase, and encrypts it using something like https://www.devglan.com/online-tools/aes-encryption-decryption
2) Baker uses a new secret key to encrpyt passphrase.
3) Baker posts encrypted text in current bread as part of bake [ eurLWBd/6I7Z/OZ7lgogxkzYAAAbwU/ZpooMmgtn1hY= ]
4) Baker of new bread posts encrypted text from last bread and secret key to decode into known passphrase.
If handing off, New baker encrypts and posts using a NEW secret key, old baker exposes secret key for current bread. [1234567812345678]
IE: Everybody can use the exposed secret key in #14064 to decrypt passphrase from #14603
Of course each confirmed baker linking to the next bread does do the same thing, except that it has to be done near the end of the bread, sometimes gets missed. Posting the encrypted key early in each bread means it's never exposed to a fumble.