Desired lambda is unusually high

I logged a WOT run in Versatuner. At high rpm and high load, I have my open loop lambda set to roughly 0.8 in this area of the graph. The actual lambda logged is quite close to what I expect, within about 3%. However, it shows the desired lambda from around 5,000 rpm up to be 0.995. I know there are other things that factor into desired lambda like ECT, etc., but I can't imagine why it would turn my 0.8 lambda into 0.995 at WOT and 8,000 rpm. That seems rather dangerous. I'm content to leave it like it is until I get an explanation. Any ideas why it's doing this?