I am also wondering if iTunes 12.6.5.3 is compatible with iOS 14.
iTunes itself sees iOS 14 is available for download, but no way to find out if it is compatible after getting the new iOS.
Edit 1:
Biting the bullet and found the SE burn phone to experiment now. Wish me luck.
Edit 2:
Cannot install iOS 14.0.1 using iTunes 12.6.5.3
Not sure if it has anything to do with this pop-up.
View attachment 959885
Thus, going through the Software Update on the phone side.
Wish me luck again... 😓
Edit 3:
The iPhone SE (original version) with iOS 14.0.1 is detected by iTunes 12.6.5.3 on Mojave.
Apps sync works.