I personally don't believe we're living in a simulation, though it's a fascinating thought experiment and I can't say for certain that we're not. This article is frankly way too definitive about questions that I don't think we're equipped to answer yet, without actually explaining itself.

The simulation hypothesis was long considered untestable, relegated to philosophy and even science fiction, rather than science. This research brings it firmly into the domain of mathematics and physics, and provides a definitive answer.

I haven't read the full paper, but the article about it says the theory is now testable, but doesn't explain how they tested it to get their "definitive answer." They also don't address the fact that their research is based on their current understanding of reality. Usually assertions like this will include something like "as technology progresses, it's likely that more questions will arise and we'll have better tools to attempt to answer them." But nope, it's just a hubristic "here's the definitive truth."

Also, the generated images are infuriating. Either hire an artist, use public domain media, or just lean on the science and leave out the images. Not everything needs meaningless pictures.