It has been brought to our attention that Retro Studios has changed the banner on its Twitter profile. It shows Samus’s silhouette, standing in what appears to be a corridor with dim blue lighting. While they have not explained the change, this concept art is not known to have been previously released. It could very well be a teaser for Metroid Prime 4.
We will update this post if more information develops.
UPDATE (February 18, 2022): An advertisement has been spotted on ArtStation. It shows another silhouette of Samus with “Your next mission awaits”, followed by the first image with “Retro is hiring!” You can see it for yourself here.