Simply is a non issue, it effects nothing.
So many tests have been done on both flash hole intrusion, dirty primer pockets and whether a pocket is factory or swaged and shows zero difference.
When seating bullets on even a slight compressed load, kernels DO get pushed into the flash hole, sometimes enough to break and flatten the kernel in the hole…
Factory pockets that are concave and have small flash holes, like Lapua, show the best consistency, changing either has proven to be detrimental to accuracy.
Food for thought.
Cheers.