That's all explained here. We wanted to be prepared for when AV1's successor arrives (AVM) and also dabble in HEVC-based releases targeting transparency rather than compression efficiency and that's exactly what we did with the release after the one linked. Equally as important was the goal to keep searches on Nyaa clean by not mixing the tag with the codec name. For example, if you search "av1" you might be rightfully annoyed to see some Sav1or idiot posting HEVC releases. In other words, we practice SEO and found that our original name was not the best decision in hindsight. We'll take a slightly harder to read name than one that pollutes search results.

And one more thing, the mention of tech companies in the link is no coincidence. I/O (Input/Output) fits our background and our ethos better and "Savior" is not a unique search term so we opted to make it look like "I/O" by using "I0". The visual similarity between "10" (binary) and "I0" is part of that consideration. And now we also steal borrow from Apple and denote quality levels of our releases with "Lite" and "Pro".