When applying online (via the ‘ANEF’* platform) for a CdS, including a renewal, I notice they have now inserted the demand for signing of the ‘contrat d’engagement’ into this process, ie agreement by the applicant to its terms is yet another condition for approving the granting of the CdS.
The contrat is a two pager basically requiring the acceptance of French ‘republican values’ eg respect for égalité, religious tolerance etc etc. Jane helpfully linked to this document a few weeks ago.
Despite the rather intimidating ‘mandatory’ wording (of the dialogue box that appears), the small print accompanying the contrat does accept that signing it is voluntary for EU nationals and their families, EEA nationals and their families, and Withdrawal Agreement Brits.
*Administration Numérique des Étrangers en France
EDIT here is Jane’s note