This is my biggest gripe after upgrading to Windows 11. Let's say there's already a running instance of File Explorer, and then you open a new folder via Everything Search or you click "Show in folder" on your downloaded file on Firefox, that new folder is going to make a new instance of Explorer instead of putting itself as a new tab in the already running Explorer. On Windows 10, I used to use this app called Groupy that catches all folders you open. I was expecting that Windows 11's Explorer would work this way. Is there any hack you can use to make Explorer behave the way I want?