I was thinking about the same thing last week. I was at 10k+ feet for about a week recently and had an AIFTP detection that was very low the following week. I have no idea how much the altitude contributed (I was also coming off taper, my “A” race, and a little rest after). But AIFTP had previously been overestimating my FTP by 10-20+ watts and this estimate came in about 15 watts lower than my physiological FTP. It was a ~30 watt drop from my last AIFTP estimate in the last month (a month where I was at peak fitness for my A race). I expect a little drop after the taper and big race effort, but the 30 watt drop is way off and I wonder if the time at altitude contributed. If just looking at my HR vs. watts from my time at altitude, I’m sure it wasn’t pretty without the context of extreme elevation. I actually adjusted my FTP manually in intervals.icu to keep my training load and ramp rates appropriate, but I have no idea how to manage it in TR. I mainly use TR as a workout catalog and calendar, so not a significant impact on my training, but it would be nice if there was a way to manage time at altitude.