i have an iphone 11 its been quite sometime since i had it. also changed the original battery once cause it went to service from apple. it runs really slow so somebody the other day told me it was because i run the latest ios software. he said you shouldnt update software for older iphones just update the required apps. is it true?
No, it’s not true. I have updated to the latest iOS available and i have no issues. If it runs really slow i would get a battery check