Nikon's 1.4x mirror-mounted telephoto mirror Z400mmf/2.8TCVRS is officially on sale. It is estimated that Canon will soon follow up, as for which one to release first,

Nikon's 1.4x mirror-mounted telephoto mirror Z 400mm f/2.8 TC VR S is officially on sale. It is estimated that Canon will follow up soon, as for which one to release first, you can look forward to it.

For example, 200-400 1.4X, 200-500 1.4x, 150-600 1.4x and so on