If GPU remains used after PL is closed, this means there’s still a program using it, or an issue in AMD drivers. I invite you to update your graphics drivers if not already done, or ask help from AMD support. Please note however that the issue that you describe looks similar to the one users are getting with AMD RX 580, see this thread for more information.
I invite you to check Windows processor requirements Windows 11 supported Intel processors | Microsoft Learn. The requirement is on the generation (year) of the processor rather than i3 or i7. What will most likely force users to upgrade hardware is missing TPM 2.0 support (in many cases you just need to enable it on your motherboard though).