Trying to understand the lock screen button on Logitech MX mechanical keyboard?

I have a Lenovo Thinkpad P16 Gen2 laptop. It also has an nVidia RTX 3500 GPU. I also have a Logitech MX Mechanical keyboard, connected by Bluetooth. My OS is Ubuntu 22.04 LTS. I have a lot of trouble with this machine staying up when I leave it. Frequent crashes requiring reboot. The best strategy I have come up with so far is to hibernate the machine when I leave it. Suspend does not work reliably. Then today, I accidentally touched the Lock button at the upper right corner of the keyboard. This immediately caused the screen to lock. I could then, by pressing any key and entering my password,

Question by Steve Cohen on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.