Choose the preferred URL
A canonical link tells search engines which URL you prefer for duplicate or very similar content. In your Astro layout, output one absolute canonical URL in the head. Use your production origin and the preferred page path; exclude tracking parameters.
Keep signals consistent
Link internally to your preferred URLs and list them in your sitemap. Each language version should normally reference its own canonical, with hreflang connecting translations. Canonical is a signal, not a redirect or a guarantee of Google’s choice.