In the fine print, OnePlus actually gives a warning against any repair attempts, saying, "The battery has been especially encrypted for safety purposes. Please go to an official OnePlus service center to repair your battery or get a genuine replacement battery." I've never heard of a battery being "encrypted" before, but I think they mean there is a serial number check in the firmware somewhere and that it will presumably refuse to work if you replace it. As for the possibility of an "official OnePlus service center" actually existing, there is a business finder on the OnePlus India website, but not one in the US, so it's looking like mail-in service only.

הנה עוד חברה שהתחילה ללכת אחרי אפל עם השטיות שלה

https://arstechnica.com/gadgets/2023/02/oneplus-takes-on-the-ipad-with-the-oneplus-pad/