We will provide detailed reproduction steps on Moodle LMS (or a test file) shortly.

When repeat_elements() is used in dynamic forms, all element ids are the same. For example, you have a "name" field in each group and 'id' attribute of the html element will be the same for all "name" fields.

This breaks for example <label for=""> elements for the checkboxes, and also fails accessibility.

For some reason it is not a problem with date fields, only with 'text' and 'checkbox' (and maybe some others)