Good to see that the spoiler syntax does work the same there. But the code block part of my comment seems to be broken for you:
The spoiler syntax should not render as a spoiler when placed inside a code block
The language hint text is not supposed to be visible at all. It is just supposed to indicate to the client what flavor of syntax highlighting should be used for that code block.
What I see on PieFed:
Also those spoilers are spicy.
Good to see that the spoiler syntax does work the same there. But the code block part of my comment seems to be broken for you:
textis not supposed to be visible at all. It is just supposed to indicate to the client what flavor of syntax highlighting should be used for that code block.