For some reason, the August 2021 update KB5005033 (as well as the July 2021 preview KB5004296) for Windows 10 put Alt+Tab out of commission. Now, that doesn’t mean that Windows will outright ignore you when you press Alt+Tab. Normally when you press Alt+Tab, it moves through your various app windows, then opens the one selected when you release the keys. G/O Media may get a commissionHow to solve Windows 10's Alt+Tab problemLuckily, we do have a workaround for this glitch, albeit a strange one. We don’t recommend this method, however, since you’ll be missing out on the crucial security patches the August 2021 update provides.

Source: The Nation August 17, 2021 16:41 UTC