Open the Google Home app; Touch and hold your device's tile; Go to Settings - Recognition & sharing - turn off Let others control your cast media
device settings, recognition and sharing. turn off the option with " let other control your cast media" :)
https://ibb.co/q1CNxhT
Press and hold on the tile, go to the gear icon, scroll down through the notifications and disable cast.
Open the Google Home app; Touch and hold your device's tile; Go to Settings - Recognition & sharing - turn off Let others control your cast media