x15 R2, downgrade to Windows 10? cause any major problems?

Responding to your points:

2. You may lose some functionality by downgrading to Win10. There may be others besides what you listed. For example, if in your country the laptop shipped with Wi-Fi 6E, that will not work in Win10.

Also, if your laptop was shipped with Win11, if you ever require warranty support then Dell may insist that you reinstall Win11.

3. You do not need a Windows product key, even if you wipe your drive and perform a clean install of Windows 11. After you connect to the Internet, Windows 11 will reactivate automatically, because Microsoft's servers will recognize your system. Assuming that your Windows 11 is currently activated (you can check it in Windows activation settings), you won't need to do anything as activation of the new install will be automatic.

Regarding your games that won't work in Windows 11, I suggest you try something else before downgrading to Windows 10. Those games and emulator may work if you install them in Compatibility Mode. Essentially, that tells Windows 11 to run the chosen applications as if they were in an earlier version of Windows. You may choose a Windows version that worked well for those games.

I wrote a post about how to install audio drivers and applications in Compatibility Mode. You can adapt my process to install your applications. Remember that a game package, or any application, may have multiple executables. You may need to manually go into each installation folder, select each .exe to open its Properties and set it to run in Compatibility Mode for all users, as I described in my post.

Thank you for the replying, never thought of installing dual-boot drive, I will give it a try!

Thank you very much!

Hi @oribesama please open online Microsoft account to register laptop and Windows products so that these can be automatically licenced without delay should there be problems. 

Download Windows 11 (microsoft.com) 

 Download Windows 10 (microsoft.com)