[Taf]

How to disable auto-playing video and audio on the new Fire TV home screen interface
From the home screen, scroll to the Settings section.
Scroll to and select the “Preferences” menu option.
Scroll down and select the “Featured Content” option.
Turn off the “Allow Video Autoplay” and the “Allow Audio Autoplay” options

or

To manage Auto Play from the Prime Video website:

Go to Account & Settings
Open the Playback tab in the top menu.
Toggle Auto Play to ON or OFF.