Fixed for me. Same issue as the rest, extra monitors not detected after Monterey upgrade. My setup is 2 external monitors connected to a docking station, Dell D6000. No monitors detected and missing the "Detect Displays" option in System Preferences->Displays. For me this was device drivers, although it is a USB C connection. Dropped into Dell D6000 support page, which put me onto installing Display Link Manager (https://www.synaptics.com/products/displaylink-graphics/downloads/macos-connectivity-1.6) although I don't recall having to do this before. Installed this and the monitors auto-detect. My "Detect Monitors" button is now also back, so although the Mac wants to reboot, I'm currently fixed.