Not sure how relevant this is but is it common to have a chunk of the filter cap rubber pop off into the vial? If that does happen I know you’d want to avoid injecting that foreign material in your body but what do you do with the rest of the vial? Filter it? Or draw as usual and visually inspect each injection to make sure it’s not in there?
I backload insulin syringes but use a 20g needle to draw so the chances of something coming off is possible.
I've always tossed the vial. I've known guys to filter it, I just don't bother with it.