This has been happening to a few people after an update. I’m guessing that something changed where the monitor’s EDID info is not getting acquired properly.
https://github.com/raspberrypi/linux/issues/5400
https://forum.manjaro.org/t/no-hdmi-output-after-update/136735
You may have to specify some manual configs. What are you using for a monitor and what is it’s resolution capabilities. Post your /boot/config.txt.