Is there something wrong with Amazon's Weights & Dimensions? OR is this an intentional money making tactic?

One of our products is foldable, and when it's packaged, the LxW fall just under the oversize threshold (around 13.75 Inches), however, what seems like every month i notice our fees jump up by at least 3-5$ per order, unsurprisingly, the product has been placed into oversized.

Of course It takes weeks for them to finally remeasure and place it back into standard size, by then, they've already taken alot more than they should of in extra oversized fees and always point blank refuse to reimburse due to the 'inconsistency of the product dimensions over time', even though we have not once changed the product or how its packaged in SIX YEARS, so the historic irregular dimensions is caused by Amazon & Amazon alone.

Sometimes I understand the reason is when new stock arrives, I assume they remeasure the item, and it may come out at over 14 inches on longest side due a the plastic poly bag being overstretched or something, but this time they are claiming the product is 27 inches in length!? Hmm, clearly not.

At this point, its become such a regular occurrence that i see the overcharged fees as just yet another expense of doing business on Amazon, but i'm just genuinely curious as to why this happens so often , and if they are doing this to others? Lets face it, if they did this to millions of sellers, thats a hefty chunk of extra money for nothing, surely its not a coincidence this happens to me like clockwork.