https://0x0.st/zFGa.bz2

rav1e --min-keyint 24 --keyint 24 -b 1000 -l 240 --threads 6 --tiles 4 zFGa.y4m --output zFGa.ivf

Artifacts can be seen around the seven seconds mark. Both keyint arguments are needed to reproduce this.
Tested on a Win10 x86_64 machine using an AVX2 cpu.