A passport is a sequence, not a single document
Material origin, manufacturing, repair, reuse, and recycling data may be supplied by different actors over many years. Each participant needs to add information without silently rewriting an earlier event. Timestamping the hash of each signed contribution preserves the order of the record while allowing the underlying data to remain in the system that owns it.
Reducing disputes between partners
When a buyer questions a recycled-content claim or a supplier changes a declaration, the parties can compare the original signed submission with its timestamp token. The result is a portable proof of what was submitted at a given moment, rather than an argument over database history. This approach also works for certificates, laboratory results, and transport milestones attached to the same product identity.