Site not secure

I’ve got a handful of Omeka sites that are showing me the “site not secure” message after being fine for months.
I don’t know how to fix this, has anyone else run into this problem or know how to fix it?

Here’s the hub site that leads to the rest of them.
http://dh-mdah.com/exhibits/

This is not an Omeka issue. Your URL uses http, a protocol that modern browsers view as insecure. Try https instead:

https://dh-mdah.com/exhibits/