In unattended mode, closing Edge thru a STOP command does not close all tabs which appaear again at next Edge opening.
In attended mode, all tabs are closed and never open again.
Set the Edge web adapter StopMethod to SimulateCloseThenTerminate and use that adapter stop instead of ending Edge with a hard STOP. In Pega, this option first sends the same close action as clicking the X on the browser window, and only terminates the process if Edge does not exit within the timeout. That graceful close is the key difference, because a forced shutdown can make Edge restore the previous session and reopen old tabs on the next launch. This is why it works in attended mode but not in unattended mode today. Once Edge is closed through the adapter’s graceful stop flow, the tabs should not come back on the next opening.