I think this is a visual bug. Whenever you get the READ/VIRUS you see purple blocks, but then whenever you get TUULI PLASMA you no longer are able to see the purple blocks making it much more difficult to tell which ones have a virus.
Yeah the game is super promising! Even for no tutorial I was able to figure out things as I explored the game. Although the outside the computer stuff I still haven't figured out yet. But overall this game is very eye-catching and just overall the gameplay loop is absolutely super fun! :D