The “CEC” in HDMI-CEC stands for Consumer Electronics Control.
What Is HDMI-CEC?
CEC functionality is not required to be included on all HDMI-equipped devices.

On devices that include HDMI-CEC, feature access is not always consistent when using mixed-brand components.
Not as comprehensive control as using the gear’s included remote or a universal remote.
In some cases, HDMI-CEC must be activated in order for HDMI-ARC to also work.
Sometimes HDMI-CEC will activate or turn-off devices when you don’t want it to.
HDMIis the primary connection standard used in the AV environment.
Along withHDMI-ARC, HDMI-CEC is an optional feature of HDMI.
HDMI-CEC may already be enabled on a unit you already own.
(Although you may need to activate it manually via the prefs menu.)
Features
HDMI-CEC provides several capabilities, which are listed below.
However, not all features listed here are accessible on all HDMI-CEC-enabled products.
Feature compatibility between brands often varies.
The feature is often referred to with a brand-specific name.
However, HDMI-CEC is not as comprehensive as many universal remote control systems.
It only works with HDMI-connected devices, and there is some feature inconsistency between product brands.
Also, as noted, the feature can sometimes unintentionally turn devices on or off.
Virtual assistants like these may end up superseding current control options.
The steps vary by manufacturer, but HDMI-CEC configs can generally be accessed using the TV remote.
Go to the television’s menu and look for controls related to the brand-specific name.
Disabling HDMI-CEC on your TV will prevent sound transmission through HDMI to other devices.