@Sebseb82 If you have an Asus USB-BT400 dongle and wish to use it in macOS Monterey, you need to use the following Broadcom based Bluetooth kexts.
BrcmPatchRAM3.kext
BrcmFirmwareData.kext
BlueToolFixup.kext
These kexts can be downloaded from the Acidanthera > BrcmPatchRAM repository, link...