iPhone 12 shows spinning wheel with black screen for few seconds and then goes to Lock Screen

I am facing frequent issue of iPhone 12 shows spinning wheel with black screen for few seconds and then goes to Lock Screen. I tried hard resetting iPhone it didn't resolve issue. Post which I did Factory reset assuming it to be software glitch as it started randomly that too didn't help either. I reached out apple care they performed diagnostic and suggested me to restore iPhone using Mac. I have done that also but issue still persisted. This is very irritating facing such issue while using phone where you have put in lot of money