dark triangles, with consistent colours, in some frames of my export.

I made an abstract animated piece in after effects, but when i went to render it, my video contained some frames with weird sharp triangles that weren't supposed to be there.
I had my friend render the same project (their PC has better specs than mine, and renders a lot faster), and the same triangles appeared, but in different locations and on different frames.

When I render a PNG sequence with AME, they are also there, but when rendering a PNG sequence from After Effects' built-in renderer, they don't have these weird triangles...

attached are:
- ame-render.png: the frame as rendered by media encoder
- ae-render.png: the frame as rendered by after effects' built-in renderer
- difference.png: both frames overlayed with the "difference" blend mode, to accentuate the weird triangles.

I was using some noise effects which had different seeds in both renders so the difference other than the triangles, isn't fully black, but they are visible enough.