I have set a release value in my Sentry initialisation call. But when I go to Releases page in my dashboard, I see my release along with some unknown ones.

The Next.js SDK includes our Webpack plugin which uploads source maps output by Next.js. The Webpack plugin creates a Sentry Release automatically and associates that release value with the uploaded source maps.

The Webpack plugin will also attempt to inject its release value to all the Sentry initialisation calls (client, server, and edge). If a release value is being provided in any of the initialization calls, the injection will fail. This will cause duplicate/extra releases being created.

Warning: When using the Next.js SDK you should only provide your custom release value in your next.config.js file. On build, the Webpack plugin will then inject this custom release value in all of the Sentry.init() calls.