Router localization with empty {locale} (sitem.com/uri_here)) - CodeIgniter 4.3

Is the following something wrong for SEO?

website.com/en/blog
website.com/en/services
website.com/en/contacts
website.com/en
website.com/fr/blog
website.com/fr/services
website.com/fr/contacts
website.com/fr

Yes. 
This is how your meta tags should look like for my example case:

<meta content="en" http-equiv="content-language">
<link rel="alternate" hreflang="x-default" href="https://website.com/">
<link rel="alternate" hreflang="en" href="https://website.com/">
<link rel="alternate" hreflang="fr" href="https://website.com/fr">

As you may have seen from meta tags, the default behaviour is to have the "en" version without the "en" at the end of your url.
If you have website.com/en - this is duplicate content for search engines. And you should be having some content on website.com (without any language at the end), right?

You can have all contents in lang directories.

    <link rel="alternate" hreflang="x-default" href="https://www.mozilla.org/">
      <link rel="alternate" hreflang="en-CA" href="https://www.mozilla.org/en-CA/" title="English (Canadian)">
      <link rel="alternate" hreflang="en-GB" href="https://www.mozilla.org/en-GB/" title="English (British)">
      <link rel="alternate" hreflang="en-US" href="https://www.mozilla.org/en-US/" title="English (US)">
      <link rel="alternate" hreflang="fr" href="https://www.mozilla.org/fr/" title="Français">

And the URL structure, "Subdirectories with gTLD (example.com/de/)" is described in the Google documentation:
https://developers.google.com/search/doc...cific-urls

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