[Update: see comment, the alembic model in the project includes NaN normals]

Reproduction steps:
1. Open attached project "AlembicTest"
2. In the Scene View, make sure that the "BackSwing" GameObject is clearly visible
3. Move around the Scene while keeping the "BackSwing" gameObject in view

Expected result: no glitching occurs in the Scene View
Actual result: Black flashes can be seen while moving around

Reproducible with: HDRP 6.5.2-preview (2019.2.0b6), 6.9.0-preview (2019.2.21f1), 7.3.1 (2019.4.16f1), 11.0.0 (2021.1.0a10)
Not reproducible with: HDRP 4.1.0-preview, 4.10.0-preview (2018.4.30f1), 5.16.1-preview (2019.2.0b6)

Notes:
1. Toggling "Post Processings" off in the Scene View makes the glitches no longer appear
2. Not every single Alembic model reproduces the issue, a simple Cube with the same material does not reproduce the issue
3. See "ReproMac_Video.mp4" for a video of the reproduction