I decided to contact the supplier, and within a day I got a response back from them.

The answer was IMHO less than satisfactory. I won't quote it, but I will tell in my own words what it was:
To their best knowledge, the hole in the end cap was intentionally made and serves a "backup function". It is to be found in other oil filters as well.
However, they always recommend to use the OEM or original filter, which they sell as well. They sell the cheap filter simply because there's a demand for it.
They will contact their supplier about the conspicuously identical printing, however they are of the opinion that the cheap filters are not counterfeits as no one says they're original.

I think that a good solicitor could wipe the floor with that last statement.
The only good thing that came out of this is that they will send me an original Volvo filter free of charge (which IMO is the absolute least they should have done).

Hopefully they will have gotton second thoughts about selling that knock off.

This counterfeit filter is probably available all over the world (maybe with "Volvo" in the print as well). Just check what the bypass valve looks like and if the rubber seal is easily removed. If it doesn't look right and the seal pulls out easily, it's fake.