I had this same exact problem. iPhone 11 max pro worked perfectly fine until apply pushed the 14.7 update to it. From there, it was constant apple loops and 100+ attempts to restore my phone with no luck. Took it to Best Buy and they couldn't get it to work, so they "offered" me a solution of buying the same exact phone for $600. I thought they were out of their mind, so I went to verizon. They had even worse options. Called Apple and the support tech was a complete unempathetic jerk. Told me the update didn't break my phone, but that something was probably already wrong, and the update exploited it. I said my phone was working perfectly well, and I didn't need an update to exploit anything. He then rambled about it being like a car transmission going bad, and he claimed that best buy offering me the $600 phone was a gift that I should jump at. Given no other options, I took that one. What a scam.