If microplastics are bad then we want to cut them out from every source were can, no matter how small.

Right.

So which are we more upset about, the tiny insignificant dose of microplastics from wearing a mask, or the ten thousand times bigger exposure from our food, our drinking water, the air we breathe, etc?

If we care only about the microplastics in masks, and not about the global pollution in our food and drinking water, then we don't really care about microplastics.

The whole mask thing is the most ludicrous culture war to get heated up over, on both sides. Masks are not going to keep you safe, and failure to wear a mask is not murder. There are plenty of people who shouldn't wear masks, but most of them are small children, and plenty of people for whom it is literally no big deal one way or another. The fact that the least important part of the pandemic response has generated the most controversy tells us that we're having the wool pulled over our eyes by both sides.

When people generate a huge amount of smoke and flame over something so unimportant, whether it is Pro or Anti, you know that there's a scam involved.