I can see from your code that there is no link information being set in the button.

<a class="wp-block-button__link has-background has-accent-background-color" rel="https://www.beyondphdcoaching.com/free-consultation/">Book a Free Consultation</a>

I think what you have done is insert information in the sidebar options for the button. You need to add a link to the button via the toolbar.

Find the button where you have added it in the editor, click on it, and you should see either a toolbar pop up or a new toolbar appear at the top of the editor. One of the toolbar items will be a link icon, click this, and enter the URL you had previously entered as the REL value.

Should do it!

Hope you’re doing well! Yes, @bonkerz is correct :).

I’ve created a screenshot with annotations on where you need to click:
https://d.pr/i/gg9Q9r

I can certainly see why that may be confusing.

Hopefully this helps!