This happened to me too, but I wasn't the one yarning. My sister was crocheting a blanket for me, but just working on it at my apartment and leaving it here in the meantime.

I also have a robot vacuum that efficiently runs around the floor every day.

Well one day, the blanket was sitting on my sofa but hanging off the edge. And I guess my vacuum sucked up the lose thread and just started devouring it while I was away.

I came back and the wheels and rollers and everything that could spin had eaten as much yarn as could possibly fit in every nook and cranny of the thing. And it took a day to disassemble the thing and extract all the yarn.

But that was just phase one. I then had to untangle the whole mass of hopelessly tangled yarn and re-form it into a neat ball. That part took a few days, and for a little bit every day, I'd shake the yarn until it slowly but surely disentangled from itself.

Luckily the blanket itself didn't unravel much if at all, and I had everything back to normal by the next time my sister visited. But it was a struggle to say the least.