good luck finding real 3m n95 with a valve today, i still have a dozen or so 3m n95 without a valve, but you can’t wear it for too long, not only it is hard to breathe but face sweating so much under it, the mask gets soaked on the edges in half an hour.
Valved N95s are forbidden in some places because they aren’t effective for preventing spread if the wearer is already infected, after all nobody can tell if the wearer was using the N95 consistently. IMHO if people that use valved N95s are diligent in taking precaution that’s not really an issue, by far the most effective way to prevent spreading Covid19 to other people is not getting infected yourself. You can wear another mask over the valved N95 but the overall effect is pretty much the same as a N95 without a valve.
Some people call valved N95 as ‘selfish’, but I think that may be the same groupthink that said ‘stop buying masks’ back in February, IMHO there is nothing selfish in stopping being part of the problem if a N95 without a valve is not suitable.