Mixed content with classic editor

Hi!

For a few days now, I can’t edit anything. I always have this message in the console :

Mixed Content: The page at ‘https://nameofthesite.fr/wp-admin/post.php?post=7366&action=edit&classic-editor__forget&classic-editor’ was loaded over HTTPS, but requested an insecure stylesheet ‘http://nameofthesite.fr/wp-includes/css/editor.min.css’. This request has been blocked; the content must be served over HTTPS.

Do you know how to fix this?
Thanks for your help, have a nice day!