Pretty sure I had an illness situation for that TT where I won but didn't PR and had crap power. I felt a tad off the day or so before and that day.
Yesterday did a 4mi run at lunch then did a mix in the evening of road and cyclocross laps. I mean, the power during that evening ride after a lunch run earlier in the day was not remotely the same as that day of the TT. Like, a lot better. Yes, the slacker stack cross bike vs TT bike. But still. Just felt strong AF in comparison, and the numbers corresponded. Like a great vo2 hill effort and a 30sec hit at 660w at the end of the ride. Power at what I would expect my 20min power is felt oddly almost comfortable.
So maybe it was illness.