Battery unknown part

Please contact Apple directly. It’s hard to imagine they would refurbish an iPhone using non Apple parts, but they can answer your question. Tap Support at the top of this page.

You can check the status of your warranty here: Check Your Service and Support Coverage - Apple Support

Where did you buy it from exactly? Who did the refurbishment? Whop said its warranted by Apple exactly?

Sounds like a 3rd party company was involved and not Apple. There's no way an actual Apple refurbished device would have that message.

You want to contact the person or company you bought it from. Apple will not touch devices that have been tampered with by unknown 3rd parties.