The modeled LTP in Xert is probably not real LT1. Some folks have done experiments with HRV and said it’s a good 10W below that.
I would take Xert numbers with a grain of salt. It’s in the ballpark, but I don’t take them as precise numbers. At one point Xert said TP is not FTP, now I think they are saying it is. At another point they said LTP is not LT1, and now it seems to be saying that it is.
I don’t think they are, as they are all based on TR’s Coggan Z2 work. From what I recall, TR’s work tends to be lower in the range, roughly mid-way in the Coggan Z2 zone. 60-65% FTP, IIRC, is where most of them land.