Hi and welcome.
I think I have posted elsewhere about issues where bluetooth is used in both Windows and GNU/Linux. What happens is that Windows 10 tends to lock the Bluetooth with the keys it creates. One suggestion I found elsewhere was identifying the bluetooth keys by searching the Windows Registry and copying these values to GNU/Linux OS.
Have you got all of the bluetooth packages installed? What is the version of Bluetooth being used? The standard GNU/Linux tends to be Bluetooth 4, but there are also additional packages for Bluetooth 5 and Bluetooth 6 which are best (easieset method) by using Synaptic Package Manager:
Just a side comment, Bluetooth mice/keyboards can't be used until the login screen is showing - one of the disadvantages of Bluetooth compared to RF.