Good question, but how sure are you that we don't see it? Lots of people got covid and don't experience long covid symptoms, so your argument is just as good at

Good question, but how sure are you that we don't see it? Lots of people got covid and don't experience long covid symptoms, so your argument is just as good at proving that covid isn't the cause as proving that marks aren't the cause. Whatever proportion of people actually complain of the long covid symptoms that could be caused by masks, maybe a similar proportion of people have effects like that in those professions, but before covid, it didn't have a name. It's hard to identify anything that doesn't have a name.