Alt-Tab is a built-in OS function and hence, you cannot disable it per se, unless you modify the registry. But, as an easier alternative, you can remap/rebind the key while in the game. In this ...

Microsoft Edge's tie-in with Windows multitasking settings probably helps other people's efficiency, but it slows me down. Fortunately, you can change how Alt + Tab behaves.

Microsoft Edge now shows open tabs in Alt + Tab shortcut, and you can customize or disable the feature – here's how to complete these tasks on the Windows 10 October 2020 Update.

In this guide, we show you the steps to modify the Registry to bring back the classic 'Alt + Tab' keyboard shortcut experience to Windows 10.

If pressing Alt-Tab no longer works as intended, there's a workaround that doesn't involve rolling back any updates.