Background in the 3D view appears black instead of transparent When in the rendered shading view the background is normally transparent, but all of a sudden it turned black. I don't know if I accidentally pushed a button, and I don't know how to turn in back to transparent.

The Transparent Film option is checked in the render properties panel.
What did I miss?
You appear to have a background image which is being displayed under the viewport render. If you disable it in 3D view > Properties region (N) > Background Images, the transparent background is visible once more: