Some in the antivaxx crowd have latched on to the disclaimers that come on mask packaging. They work backwards illogically to mistakenly conclude that if the item doesn't promise to work, that means it doesn't work. Two of them post to my local NextDoor. I got emails about them but both posts were gone by the time 3 or 4 horus later when I had time to read them. Removed by sane moderators.
But I answered them anyhow:
Let me add that there are disclaimers on the boxes or wrappers that masks come in because they don't give 100% protection and without the disclaimer, people who did get sick, even when it was there own fault, would sue the mask maker. They would probably lose (reasons below) but the maker would have to hire a lawyer, spend company time in "discovery", etc. It might be the wearer's own doing, or even his own fault, because he didn't wear the mask all the time he should, he wore it below his nose, he pulled it partly off to talk (which is not necessary. If they can't understand you, just talk louder), he took it off to eat in a public place, he didn't wear it when he was home but someone in his family got sick elsewhere and gave it to him. And I'm sure I've left out other reasons.
If a disclaimer says No protection**, instead of Only partial protection, that's what their lawyer recommended so they won't have to fight in court about how much protection there should have been, how much there was, in addition to if that's why you're sick, and what the damages should be. **[Someone provided a picture of the cheap blue pleated paper masks. I'm sure they provide some protection but I would not use something so flimsy. I wore N95 until the 3 I had got old and now I have KN95.]
But the disclaimer doesn't make the masks any less protective, any more than a warranty on a cellphone that is only for one year means the phone won't work just as well when the year is over.
People who claim that masks don't work because there are disclaimers are making a big logical mistake and they don't understand how the legal system influences what is written. But the masks still work well. That's why the infection and death rates following surgery went down so much when surgeons started wearing masks
I'm not a lawyer but... There are disclaimers on just about everything you buy, but we've stopped reading them. Many are contained within the warranty information, for small and large appliances and many many other things. What looks like the manufacturer is going beyond the call of duty is often the opposite. The 2-year warranty may sound like a long time, but it is likely a limitation on the common law warranty or a UCC warrantyh which has no particular end time and could be interpreted, by the user or by a a court, to be far longer than 2 years. I think radios should last at least 20 years and I have radios that still work after 90 years (my uncle gave them to me.) Ninety. So these warranties are mostly disclaimers, but I don't disapprove of that. If they had repair or replace a radio that failed after 19 years, they'd have to charge more for the radio in the first place.
And if they let people think that masks were certain to prevent you from getting sick, a) that would be immoral, and b) instead of $3 dollars masks would be $300, to pay all the legal expenses that would follow. And not only that, c) people would relax the other precautions they should be taking. (They've found when they started including airbags or maybe it was ABS brakes or some other safety feature in cars, that some people just drove faster because they thought they were safer. They were safer until they drove faster.)