Midjourney or Firefly for client work: which one can you actually license?

Here is what I found, so someone can tell me where I am wrong. I am an art director at a small agency and I am not a lawyer.

Midjourney's terms of service say you own the assets you create "to the fullest extent possible under applicable law", with exceptions. Your ownership is subject to the rights of third parties, and a company with more than 1,000,000 USD a year in revenue has to be on a Pro or Mega plan to own its assets. The same terms provide the service "as is", with no warranty of non-infringement, and ask the user to indemnify Midjourney. Nothing in there protects us if an output resembles someone's work.

Adobe's Firefly FAQ says outputs from features without the beta label can be used in commercial projects, and describes the model as trained on Adobe Stock, openly licensed and public domain content. I could not find an indemnity promise on that public FAQ. Enterprise contracts may say more, but that is a conversation with a rep and I have not had it yet.

What I still want to know:

• Does anyone have a signed agreement, not a marketing page, that covers IP claims on generated output?
• How are you handling client approvals? We have been adding a line to the estimate saying which parts were generated and which tool.
• Where does "I own it" stop being useful if the output may not be copyrightable in the first place?

The client is a retail brand with a legal department that will read anything we send. I would rather bring them a short, accurate memo than a vague reassurance.