My guess was that it had to do with the A and AAAA records, so I deleted them, but then the site did not load at all and I had to add them back again last night.
I’ve read over and over the posts in the forums and the support pages, but clearly something is escaping me.
The reason your site is still served via OVH is because of the A and AAAA records you have added.
$ dig www.coworkinghandbook.com
www.coworkinghandbook.com. 4114 IN A 51.91.236.193
and
$ dig coworkinghandbook.com
coworkinghandbook.com. 4106 IN A 51.91.236.193
coworkinghandbook.com. 4106 IN A 75.2.60.5
In both examples above 51.91.236.193 is an OVH IP address. 75.2.60.5 is the Netlify load balancer IP address but you only use this when configuring external DNS. The AAAA records are also OVH IPv6 addresses.
When using Netlify DNS you don’t add A, AAAA, or CNAME records to have Netlify serve a site, you need to add a domain to a site as a custom domain. Netlify then automatically adds the appropriate NETLIFY type records to serve your site. See the Assign a domain to a production site documentation for more.
You need to remove all the A, AAAA, and CNAME records you have created via the Netlify dashboard.
You need need to add the domain following the assign a domain to a productiion site I linked above. As mentioned, this automatically creates the appropriate DNS records (NETLIFY type records) to serve your site.
You may find the resources in this topic useful too