Bird netting with holes big enough for bees is unlikely to cause poor pollination. Bees are very good at sensing and reaching their food sources.

Bird block can definitely hinder pollination, at least in my locale. The small holes seems to block out a large number of honeybees, the big bumbles, hummers and possibly the smaller hover bees. My observations have been that pollinators prefer unfettered access. Put the bird block on after fruit set to be safe. There is nothing to be gained by blocking birds from flowers, and possibly grabbing a buggy meal that helps you in the long run.

Word to the wise, birds are good to have around. They are fun to watch, make nice sounds, and remind us that we share living space with other creatures. No birds = no humans. Block the birds from your fruit if they are taking more than their share. But do remember to leave them some fresh water in multiple locations - I have found that this makes them less apt to peck at fruit. I'm bird friendly and have never had a devastating bug infestation in almost 30 years at the same location.

I should add that squirrels and rats are deterred somewhat by bird block, my guess is that they think it is some kind of trap. Again, I would wait until after fruit set to apply the bird block to deter rodents.

I put bird netting over my plants and it did hinder pollination. The problem I have is a mix of SHB and Rabbiteyes in the same area. I waited as long as I could to put up the netting but once my SHB berries started turning color I had to put it up. The problem was the Rabbiteyes were still flowering. I didnt notice any more bees in side the netting and actually saw several bumble bees attempt to get to the flowers but quickly turned away once seeing the netting. Thankfully most of the flowers were already pollinated on the Rabbiteyes but I still missed out on some production. That may not be the case everywhere but that was my experience this spring.