Hide the idle app, then quit it
The Dock is yesterday
Safari, Mail, and Xcode stay in the Dock after you have not touched them for hours. Closing the window left the process running. It still holds memory. Some of those apps still refresh. macOS will not tidy that for you.
A Premiere render, a download, or a Logic session you stepped away from is not the same thing. Idle has to mean forgotten.
What it will not close
Auto-close is off until you turn it on. Then an idle app hides first, and quits after a short buffer. You can whitelist one, snooze one, or set a per-app threshold.
Premiere Pro, Final Cut Pro, Logic Pro, and Finder are never closed. Figma, Photoshop, and similar apps get a 2-minute warning. Known editors are checked for unsaved documents before a quit, and if the document is dirty the app stays open so you can save it yourself. The check does not read the file and it does not capture the screen.