The symptom is specific: canonical tags point to unrelated pages. Start with the affected item and identify the decision or input that could produce this behavior.
Find the likely cause
A template default overrides the actual content relationship.
Treat this as an explanation to verify against the actual work. Look at the input, the relevant decision, and the final result together. If the evidence does not support this diagnosis, investigate the mismatch before applying a convenient but unrelated fix.
Make the targeted correction
Set preferred destinations that match the page's substantive content.
Canonical handling should express a consistent preferred version while preserving a useful experience for visitors.
Check that the repair worked
Compare the source and destination before approving the tag.
Repeat the check on the final version that the reader or customer will encounter. An approved draft, a preview, and a published result can differ; the acceptance decision should concern the version people actually use.
Prevent the next related failure
A separate issue to watch for is this: a canonical points to a broken destination. Replace the destination with the correct working preferred URL.
Monitor the useful outcome
Track conflicting canonical declarations and whether important pages remain discoverable and usable.
Keep a short record of the original symptom, the evidence behind the diagnosis, and the result of the acceptance check. That record makes the solution reusable when the same condition appears again, without assuming that every superficially similar problem has the same cause.
Official reference for the platform or standard discussed: Google Search Central: canonical URLs.