those are the values shown yesterday within the buckets data field (Edge 830, latest DF version).
Screenshot from Garmin connect, where those values also get reported:
In contrast, xert online shows those values:
So basically they all (high, low, peak xss) slightly differ: 92 vs 90, 14.8 vs 15.2, 2.5 vs 2.6
This is a consistent observation during my last rides and it makes training planning and execution somehow unprecise.
Is that a bug in one of the two (bucket DF, xert)?
I have seen similar discrepancies. I suspect that XSS buckets looks at your adapted forecast, even if you haven’t pressed “Adapt Forecast” on the website. But I am just speculating.
Second by second data analysis is more robust on XO when the activity is uploaded to the server.
I don’t think a Connect IQ data field can match the same level.
Another factor is signature adjustment. A BT during the ride would significantly change the result compared to original target values. A minor daily adjustment can also occur especially after a long and/or hard ride. A point or two would make a difference in the final analysis.
I don’t think the numbers need to be precise for training purposes especially when riding outdoors.
I think that is the reason, signature is updated before xss are acounted for the activity, while the bucket field bases all calculations on the initial signature from before the ride.
@xertedbrain Is that the reason? Anything you could do about that discrepancy?
I agree that the effect is minor in the grand scheme of things, but that´s not how I see it while returning from a 1…2h interval session where I just summoned all remaining will power to crank out the last 0.5 high-xss, dreaming about kicking that bike in the ditch and switching to bowling for the rest of my existance, just to learn that xert substracts 0.5 xss from what I suffered for! 
Today the discrepancy was more extrem.
Buckets/Garmin connect:
Xert:
1.2 difference in high-xss, quite annoying 
For the workout portion of the ride do you roughly follow XATA or XFAI advice with Target Watts in mind along with Focus and Specificity at the suggested Difficulty level?
Then concentrate on filling any bucket showing a point gap before ending the ride?
Not really following advises as that´s too static for my daily life.
But well, as said, it´s more a motivational thing than something which really impacts my training or results.
I too have seen a difference between post-ride numbers and the bucket numbers. For me it was obvious because I proudly met my High goal of 12.7 (at 13.0) on my bucket only to see it as 12.5 later on-line. Yes, not very important (4% difference), but a bit annoying.
Were the Moderate Mixed Pursuiter and Difficult Pure Breakaway Specialist activities strictly random results based how you rode the route that day or did you have specific HIT workouts in mind?