how to reproduce

• go to the demo : https://demo.ametys.org/nightly-intranet-cms/intranet/index.html
• create a reporting form with the help of the doc https://docs.ametys.org/fr/ametys-v4/releases/nouveautes-ametys-4-7/charte-intranet/formulaire-de-signalement.html
• make the rich text field mandatory
• insert the form into a page

go to the preview
the following text is displayed: "Les champs suivis d'un astérisque * sont obligatoires"