Repro steps:
1. Import the attached VFX
2. In the scene view, observe how some particles are flickering
3. Reduce the count to 4096
4. Observe the particles no longer flicker.

Note:
- the more particles, the more obvious it is
- not a very visible issue, only noticeable with static particles and static camera
- not a regression, an older issue (added 6.0.0 as the found version, but was probably there since GPU sorting was introduced)