Question about LFO-CV vignette

I am just learning LOO and I’m going through LFO-CV vignette and wondering if I am misinterpreting what is happening. It looks like the log likelihoods are being passed into the PSIS function directly in creating the approximate 1-step ahead predictions instead of the log ratios. They are called log ratios, but I don’t see anywhere in code where the likelihoods are transformed into log ratios by multiplying -1. Do they need to be log ratios for using PSIS function, or does PSIS take log likelihood directly?

Thanks for the attention.

The difference comes as we are adding observations instead of removing them.