Moonlight streams the foreground window. When you Alt+Tab, the foreground changes. If you are using (often launching a specific game via the "Play" button), the stream session is tied to that game’s process ID. Alt+Tabbing breaks that tie, forcing the stream to either disconnect or show the desktop.
From a cognitive load perspective, the Alt-Tab moonlighter engages in a high-frequency task-switching regimen. Research in attention residue (Leroy, 2009) suggests that moving from a primary work task to a secondary personal task leaves a cognitive trace; however, the Moonlight Alt-Tab scenario involves concealment residue . The worker must not only switch tasks but also maintain a "cover state"—keeping the primary work application in the peripheral vision or ensuring the secondary window is instantly dismissible. moonlight alt tab