Duplicate Pages For HTTP and HTTPS

When running a Screaming Frog scan, I'm seeing a lot of pages duplicated because both HTTP and HTTPS versions exist. The HTTP version shows as Canonicalized and the HTTPS version shows as Non-Indexable.

The site doesn't automatically redirect all HTTP requests to HTTPS.

I'm very familiar with resolving these problems on WordPress and other platforms but not sure how to address these issues within the limits of Squarespace. Any help would be greatly appreciated.

Snap, me too. I'm also getting backlink reports from duplicate pages hosted on the SQSP built in domain. (These duplicates are also canonical) I messaged SQSP, hoping they have some option on this.