Setting up local Mac environment, and noticed that after Iterm2 / Oh-my-zsh / Powerlevel10k
installation, when I click on any area in the terminal, it will highlight the session and grey out other area (please see screenshot)
I am not sure it is a behavior from powerlevel10k or oh-my-zsh or even iTerm. Please kindly help
The highlighting you're seeing is part of iTerm2's Shell Integration feature, specifically a functionality called Command Selection.
Click on a command to select it; then Find, Filter, and Select All will be restricted to that command's output.
While useful, it can be disabled by unchecking the option "Clicking on a command selects it to restrict Find and Filter" under Settings > General > Selection.