After staying in a very busy sector for a while I see a bunch of weapon effects that aren't moving. They only disappear when I leave the sector. It's kind of hard to explain and a screenshot probably wouldn't show it either. It's as if somebody fired guns with 0 velocity.

I've only noticed this in levi sectors and during border skirmish till now.

Sounds a bit like the old bug where Collectors' mining beams wouldn't shut off if they were destroyed without "noticing" that they were under attack.

Out of curiosity, did you try to run into them?

I just fly through them if I try. So it's really just the effect.