Does your PS5 always turn on at the same time you turn your TV on?
Well, there's a setting to stop that from happening. It's called HDMI-CEC, which allows for your TV to communicate with other devices connected via the HDMI port, such as the PS5.
To turn this feature off completely:
Turn on your PS5, then select the Settings cog from the top-right corner.
From there, go to Settings > System > HDMI. Then disable HDMI Device Link.
However, if you do not want to turn off this feature completely, within this menu there are two sub-options to consider using. Enable One-Touch Play controls whether your TV turns on when you boot up your PS5. Enable Power Off Link is the option that makes your PS5 go into Rest Mode when you turn off your TV. You can disable one but not the other if you like.