Apple sign-in issue

I currently am setting up the sign-in for Apple onto my website. I followed this tutorial: https://www.youtube.com/watch?v=6I2JEky20ME&t
It's from a few years ago, so I'm not sure if it's completely up-to-date. But I did that and set up my Supabase with how they told me to. When I now sign in through Apple with my website, I just get sent back to the landing page after I go through the apple sign-in stuff and my login page. The url I am on is actually this:
https://www.clashscan.com/?error=server_error&error_code=unexpected_failure&error_description=Unable+to+exchange+external+code%3A+c7763e639c2794775bddbd0ebb231e52c.0.srqzt.cAzVstPgVNfJgDWQlgvB7w#error=server_error&error_code=unexpected_failure&error_description=Unable+to+exchange+external+code%253A+c7763e639c2794775bddbd0ebb231e52c.0.srqzt.cAzVstPgVNfJgDWQlgvB7w

I go about diagnosing/solving this issue.

How to set up Apple OAuth for your Supabase application so your users can click a button to authenticate using their Apple account.

Source code for secret_gen.rb: https://gist.githubusercontent.com/janakamarasena/cb1ebb4abec8c903329cb25ecb6fe562/raw/527a92902abbbca01bfb025a544580275f6f8b44/secret_gen.rb

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