One of the new features that Windows 10 offers since the second update in 2020 are multitasking: you can now use the Alt+- Tab keys to switch between not only active apps but also tabs opened in the Microsoft Edge browser. What exactly appears when you press Alt+Tab is up to you.
Open the Dashboard, for example, by pressing the Windows+I shortcut or clicking the Start button with the gear icon, then click the System category and select the More Apps entry from the left-hand column.
In the main window, in the area under Alt+Tab, you will find the When Alt+Tab is pressed option. Open the drop-down menu underneath and choose from the four available functions, such as this one: Open windows and Show all tabs in Microsoft Edge.
If you are using a different browser, then Show only open windows is the optimal choice.