Even though you don’t know it, you probably have an app (or several), music or something else that transferred over from your old device that was originally downloaded or purchased using your old account. If you delete it, it should stop prompting. If you can’t figure out what it is, setting up as a new phone should work.
I had an ender 3 as well. Every time I used it I had to calibrate and level it, and watch the the print for the first few layers to make sure it was going to work. I’d estimate it had failed prints around 50% of the time. Eventually it died and I got a anycubic kobra printer. It is so much better it’s unbelievable. I leveled it once when I first assembled it. Since then I haven’t calibrated it or leveled the bed once. I’ve done over 100 prints on it with a 0% failure rate. It is truly a printer where I can tell it to print something and come back 10 hours later and have a perfect print.