With Nexus 7 LTE (deb) and OTA-12 rc (2020-W14), pressing the power button and releasing it quickly to just switch off the screen, activates the power-down menu as if the button had been pressed for a longer time. Then the screen does indeed turn off. Pressing the power button again, turns the screen back on, with the power-down menu still present. To use the device you have first to press the cancel button. This is quite inconvenient when you have the habit of switching off the screen manually to save charge.
The issue is not present with OTA-11 (tested switching back and forth between stable and rc channels).