In Material Design Guidelines it is covered the case when the optional fields are fewer:
To indicate that a field is required, display an asterisk (*) next to its label. At the bottom of the form, mention that asterisks indicate required fields.
To indicate that a field is optional, display the word “optional” in
parentheses next to the field label.
In forms with some required fields, indicate all of the required ones.
However, if there are fewer optional fields, indicate those instead.
It makes sense that if most of the checkboxes on a form require being checked, indicating all required fields would add unnecessary info to the form. The problem here is that in your case all the checkboxes are required, In this case, you can't practical indicate the ones that are optional.
In my opinion, add a single message "All the terms above need your attention" / "All fields are required" is the best option. You will have less visual clutter.
Another alternative would be to not indicate optional/ required fields in this case but handle missing required checkbox with error messages.