Time for Quest -80%

Not really, but they are allowed to do as a showcase/project to promote their game.

Are they the dev?

Here is what the rules say:

Game Showcase

You are invited to share your Steam game in this category when you are a game developer. You can show us your work-in-progress, let us know when your game launches on Steam, or poll our community for feedback. We encourage you to provide additional information about the game, such as a description, what you are trying to achieve, why we may find it interesting, or how your game differs from others in the same genre. You are limited to one open discussion per game. Be considerate to not repeatedly bump your content if the community is not engaging with your post.

Now they have 3 open discussions and only post a sale with no actual discussion. Kinda falls in the spam category in my opinion.

You are not the only one XD