Comparing a new batch against an old one. A loose blister is different in a way that may be nothing.

Reagent tests are a screen, not an assay. They rule a family in or out and say nothing about dose.

A smell that is wrong is a reason to look closer, not a verdict. Excipients do most of the smelling.

Foil thickness and seal pattern are where counterfeit blisters fail.

Genuine cartons have print that aligns to the die cut. Copies drift by a millimetre or so.

Any ideas welcome, and I will report back what the pharmacist says.