Yeah, my Aurora-R6 (with 7th Gen Intel processor) also works fine with Windows-11 ... it just needed a clean-install. The clue is that the TPM-2.0 (and everything else) passes the Windows-11 Ready-ness Check. Only the Intel i7-7700K fails (for NO GOOD REASON). Pretty lame but clean-install of Windows-11 Pro (64 bit) installs and works perfectly. What you describe is an old problem from Windows-8 days.  Control Panel / Device Manager / Bluetooth Radio / Properties / Power Saving / tell it to stop powering down to save power. You might have to do it to the mouse itself also, but IIRC ... it's just the BT radio device.
  Hello, Since I moved to Win11 (xps 9365 is not supported by Dell !!!!!!!!) I've continuosly experienced lag problems with the BT mouse. Basically whenever the mouse goes idle it takes up to 2 seconds before being responsive again. That makes it pretty much unusable. I researched here and there, upgraded BT drivers and windows but mouse keeps stuttering. That happens on both BT mice I have: a logitech and a HP. It seems that downgrading to W10 is the only possibility. Thank you, Davide
BT mouse lagging on XPS 9365