Why is Chromecast icon always showing up when changing volume?

[Android_Asker]

I don't cast anything, but everytime I change my volume (no matter whether it is with my headphones connected or just phone speakers) the icon of Chromecast always appears blinking in the volume panel. I have the latest software. It's been for almost a year now and I tried a lot of ways to remove this constantly appearing icon.
What could possibly make this icon appear? Thank you.

Phone: OnePlus 8

Please, follow the link to Google Drive to watch a short video of how it looks like:
https://drive.google.com/drive/folders/1tf6HFYpU_PVysufxLrsrOImOMY-8mOuw

Thank you bet much.

 

[B. Diddy]

Welcome to Android Central! So you don't have a Chromecast at all? Do you use a wi-fi network that's shared with other households (like an apartment network)?