I contacted Dell Tech Support and they want to replace the motherboard and hardware for the USB ports.  So, you can close this case.  Hopefully, the hardware changes will make a difference. 
Hello My Dell Bluetooth keyboard and mouse randomly fails.  These are Dell devices that used to work well with my Dell XPS Windows 10.  With my new Dell XPS XPS 8940 Windows 11 PC, the keyboard and mouse would work for a week or so and then stop working.  I would have to plug in a wired USB keyboard and mouse to use the PC.  I have tried many things: None of these things resolved the issue.  The thing is that the articles and posting that I find are for getting the Bluetooth mice and keyboards working.  For me, they are working for awhile and then stop. I like to avoid getting a new Bluetooth mouse and keyboard as I am wondering even if I get new devices, they still may randomly stop working. This is related to Windows 10, but I wonder if the issue has not been resolved with Windows 11.   [URL] I do see this in the event log that seems to occur every time the keyboard and mouse stop working. But articles that I find don't help.  Error keeps occurring: Log Name:      System Source:        BTHUSB Date:          5/24/2022 8:44:40 AM Event ID:      18 Task Category: None Level:         Information Keywords:      Classic User:          N/A Computer:      Home Description: Windows cannot store Bluetooth authentication codes (link keys) on the local adapter. Bluetooth keyboards might not work in the system BIOS during startup.
Dell Bluetooth Mouse and Keyboard Randomly Stop Working