OAuth - "redirect uri mismatch"

Question

I've been battling with this Google Login for a while now(+2 weeks) and pulling my hair because I don't understand what is causing this error for me.

Context: Rails 7 API trying to send a HTTP request to eXchange my Authorization Code for an access token from Google.
Error: "error": "redirect_uri_mismatch",

GOOGLE_AUTHORIZATION_URL=https://oauth2.googleapis.com/token

# Redirect URI
REDIRECT_URI=https://63cd-106-185-157-124.ngrok.io/auth/google_oauth2/callback

[Google Console] [Ngrok Running]

My method getting the authorization code and then sending the request:

 def self.get_access_token(auth_code)
    conn = Faraday.new
    response = conn.post(ENV['GOOGLE_AUTHORIZATION_URL']) do |req|
      req.headers['Content-Type'] = 'application/x-www-form-urlencoded'
      req.body = URI.encode_www_form(
        code: auth_code,
        client_id: ENV['GOOGLE_CLIENT_ID'],
        client_secret: ENV['GOOGLE_CLIENT_SECRET'],
        grant_type: 'authorization_code',
        redirect_uri: ENV['REDIRECT_URI']
      )
    end

    if response.status == 200
      puts "Successfully authorized code and got access_token"
      puts "Response body: #{response.body}"
    else
      puts "Failed to get access_token."
      puts "Response status: #{response.status}"
      puts "Response body: #{response.body}"
    end
  end

I started out with sending my request with this redirect_uri: http://localhost:3000/auth/google_oauth2/callback whichis also added in my console, but it gave me the same error error: "redirect_uri_mismatch

I changed over to using ngrok and HTTPS as I read somewhere that it is required?

• Restarted my app plenty of times
• Waited for over 24 hours after adding my URI
• Tried restarting from scratch

Grateful for any help. Hope someone can point out something stupid I missed.