Bug or not?

I don’t understand why my sensor icon is shown on my temp diagram …
Is this a bug?

Entity name it seems?
The sensor seems to be named sensor.temperature_14

Yes … understand but how can I erase that on the diagram?

That is how the graph card was designed.

So no it is not a bug.

You can change the entity name if you want to but you can not remove it from the graph legend.