In ACF, if we modify labels, descriptions, or options of a field, the value of field_nnnn remains unchanged. However, if we change the meta slug, a new field_nnnn is generated. This causes the existing data in post_meta to become orphaned.

It would be better if changing the slug did not affect field_nnnn, so the link with existing data stayed intact. On the other hand, if we create a completely new field, then a new field_nnnn should indeed be generated.

Thanks