@niko I bet what you did is mute the topic. This makes it basically go away as you’ve noticed.
To find it again, click on your profile icon and go to preferences (the gear). Go to Categories and you’ll see a link to see your muted categories. You should then see it there.
If you’d like to unmute it again, go to the topic and click this little X icon in the right sidebar.
Here’s the Amazon topic: Amazon HQ2 Downtown?
and here’s the X icon.