AGM Shareholder Questions, page-42

I haven't dived into this above matter, yet from my (non-technical) experience in the industrial chemistry sector, the chemistry can often surprise us.
All lab tests are subject to a certain level of tolerance. You might do 19 tests and then bang on number 20 something creeps and you can have a profoundly different result.
In addition to the environmental and equipment variables mentioned above, there can also be variances in the various chemicals and testing mediums - often arising when a laboratory changes supplier, or their supplier changes supplier! This is a common occurrence in covid times...