According to the following documentation, after you upload a Managed - Released package that contains a custom metadata type, you can’t:
- Add required fields to the custom metadata type.
- Set non-required fields to required.
- Delete custom fields that are in the uploaded version of the package. If you add a custom field after the upload, you can still delete it until you upload a new Managed - Released version.
- Delete public custom metadata records that are included in the package.
- Change a public custom metadata record or type in the package to protected. You can, however, change protected records and types to public.
- Change the manageability of any custom field in the package.
Now, none of these constraints pertain to the ability of changing required fields to not required. Yet, the page layouts do not change required fields to not required after such a change. Any reason why?