This morning my Lenovo X1 gen8 could not detect an external display via HDMI. Another display, connected via USB-C, is also not detected (even though the built-in USB-hub works with mouse/keyboard).
Yesterday evening everything worked fine.
xrandr does not even list the external displays. The only thing I tried so far, was to update the kernel but it did not help (restarting the machine did also nothing).
Would you have any pointers on how to start looking into this problem?