Perhaps a chemical reaction over time? That'd slow the flow if it is. maybe there's Chinese and Chineez.
I don't think that's it, but who knows. I've cut a couple apart and the filter media inside doesn't look like it would slow flow at all, the cover over it looks to be more restrictive. I've taken used dirty ones and poured gasoline through the nozzle on the filter and it runs through with no resistance, but that is reverse the way they normally flow. Maybe that cover gets clogged enough that the filter collapses under suction?
Another oddity. You hear of the filter showing as a problem when the bike starts dying at idle, way more than they start bogging under power. That never made sense to me as the flow through them at idle has to be very low. I don't know if that shows it fails in two different ways or not.
And another oddity, Suzuki actually calls it a fuel strainer, not a filter. Everyone else calls something like that a filter, but maybe they don't intend on it to actually filter, just to strain out larger particles. It might be just semantics but I always found that odd too. And they aren't really consistent on that, the parts list calls it a fuel strainer, the service manual calls it a "fuel mesh filter".