Does anyone know what Apple's policy is to protect battery problems?

I bought the iphone15pro in January 24. Almost a year after this year, I found that the back cover was tilted. Recently, I found that it was getting more and more irritating, so I took a closer look and found that the back cover was tilted even higher. So I suspected that it was a battery bulge, and then it was said on the Internet that no matter how long the battery problem lasted, Apple could replace it for free and extend the warranty. I believed it. I made an appointment with genius bar, but there is no directly operated store in Xi'an, only an officially authorized repair point like Baibang. The staff said that if it is guaranteed, it is out of warranty. They have no right to replace the battery for me for free, and if I want to confirm the problem, I need to disassemble it. Look, the disassembly fee is 199, and the battery seems to be 900. Then I called apple's official customer service, and they also said that apple only guarantees that there will be no quality problems within one year, and they will ignore all problems after the warranty. Then they said that they can only adopt the hardware department's out-of-warranty policy. So this kind of battery problem, battery bulge problem, is it really only guaranteed for one year? What if it blows up one day... I use my personality to guarantee that the mobile phone will never be dismantled, repaired or bumped. It is purely a quality control problem. I don't know what to do.