All entries in the scope of a CoS definition, for which the computed CoS attribute is generated, also contribute to computing its value.
When the CoS attribute already exists in a target entry, by default, the CoS mechanism does not override this value. If you do not want this behavior, define your CoS to override the target entry, or protect the CoS attribute in all potential target entries.
Both indirect and classic CoS also rely on a specifier attribute in the target entry. This attribute specifies the DN or RDN of the template entry to use. You should use an ACI to protect this attribute either globally throughout the scope of the CoS or individually on each target entry where it is needed.