Web Browsers Prevent System from Going to Sleep

Your web browser may prevent your system from going to sleep. You can override this by running the following commands in an elevated command prompt. Note, the commands below sets the override for Chrome, Firefox, and Edge.

powercfg /requestsoverride PROCESS chrome.exe AWAYMODE DISPLAY SYSTEM
powercfg /requestsoverride PROCESS firefox.exe AWAYMODE DISPLAY SYSTEM
powercfg /requestsoverride PROCESS MicrosoftEdge.exe AWAYMODE DISPLAY SYSTEM

Reference
https://techjourney.net/chrome-prevents-windows-from-going-into-sleep-standby-or-hibernation-mode/