1. It adds extra latency due to an extra hop.

2. It is non-bypassable tracking of every single click.

3. It does not allow you to inspect the URL to see where it goes to before visiting.

4. It breaks the feedback signal of extensions which redirect sites. E.g. Fandom wikis are shit so I have them redirected to equivalent much better wikis like. But now any such redirection has to be done post-click tracking meaning Google still believes I want to see the Fandom site.

5. It breaks extensions which hide certain shit search results based on URL.