The further volumetrics are far away, the more this happens. Light or camera parameters don't have an influence on this, only distance / rotation.

Here's a video that demonstrates the issue: https://i.imgur.com/YtVj0xc.mp4

Note that this is is independent of the camera's field of view for some reason: https://i.imgur.com/IRIXLbc.mp4

You can also notice this happen on the "start" of the beam as well, by the way: https://i.imgur.com/lvo3wYS.mp4