Which plugin is this?

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The image shows a screenshot of a Discourse page with a job posting, indicating that the platform is growing and hiring. (Captioned by AI)
The image shows a screenshot of a Discourse page with a job posting, indicating that the platform is growing and hiring. (Captioned by AI)1207Ă—193 14 KB

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The “dismissable hiring banner” is a custom component.

Some ways to create a banner are explained in Creating a banner to display at the top of your site. There are also other #theme-component which add a banner, like Notification Banners