I accidentally clicked the circle with a line through it icon and a song that I enjoy has been removed from my playlist.
The first time I hit the button, I wasnt sure what the message said. So I tried clicking it again so that the notification would reappear and I noticed that yet another good song was removed from the playlist. Then, I clicked the banner at the bottom of the screen, and now the artist is completely removed.
I think there should be an option to reset the "banned" songs and artists in the daily mix. Or even an notification should display the first time the button is pressed (for new users) to state what the button does and ask "are you sure?".
Updated on 2019-04-08
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There's now an undo popup when you click dislike on a song on Discover Weekly, Release Radar and Daily Mix.
Once you've clicked it, you'll get a message confirming that you've undone the dislike -
This happens on both Desktop and Mobile.