What are these weird black lines in my composition?

[Ruben276755703hdm]

I am working on a animation and encountered something weird. In some frames there are these strange black lines showing for 1-2 seconds. Please see the screenshot.

I am curious what causes these lines to show.

Specs of my composition:

1080 x 1350 px (4:5/0.80 aspect ratio)

Square pixels

30 fps

After Effects version 25.1.0 (Build 68)

[balian_2014]

The black lines in your composition could be due to corrupted frames, graphics driver issues, or glitches in the preview rendering. Try purging the cache in After Effects (Edit > Purge > All Memory & Disk Cache) and ensure your GPU drivers are up to date. If the issue persists, check for any plugins or effects causing conflicts and render a test output to see if the problem exists in the final video.