Content Aware Fill was introduced in Photoshop CS5 (supposedly, I cannot really remember myself).
When sticking with obsolete software one should exercise caution with newer tutorials etc.
Yes, it was CS5.
Why did you title this thread »Selections« when the question actually concerns fills?
Content Aware Fill no longer works in my Photoshop 2021 after installing MacOS Big Sur. Gotta fix for this somewhere?