Missing primary key for table `death`?

Table death does not have a primary key, although this would help with data integrity. How unique are rows in that table?

My initial thought is that person_id can be a primary key in that table -- as all can be anticipated to die at most once --, but I am unclear
about whether death_type_concept_id and cause_concept_id model a 1:1 relationship with a death event. If not the case, and a death event can be associated with multiple death types or causes, a different primary key should be used.

This is currently present in all three versions 5.3, 5.4, and 6.0.

5.3
https://github.com/OHDSI/CommonDataModel/blob/d83d48c2ba1b641879c33958903f630318421cb8/inst/csv/OMOP_CDMv5.3_Field_Level.csv#L181-L187

5.4
https://github.com/OHDSI/CommonDataModel/blob/d83d48c2ba1b641879c33958903f630318421cb8/inst/csv/OMOP_CDMv5.4_Field_Level.csv#L193-L199

6.0
https://github.com/OHDSI/CommonDataModel/blob/d83d48c2ba1b641879c33958903f630318421cb8/inst/csv/OMOP_CDMv6.0_Field_Level.csv#L185-L191

Start by comparing the death-table field definitions linked for OMOP CDM versions 5.3, 5.4, and 6.0. Determine whether person_id uniquely identifies rows and whether death_type_concept_id or cause_concept_id permit multiple records per event. Done means the key decision is resolved and the affected model definitions and DDLs are updated consistently across all three versions.