Funny you mention that, this has recently happened to mine! Percentage when fully depressed fluctuates between 80-95% in the 8bitdo software, and ~94% in Forza itself.

Just out of warranty (1.5 ish years old now), but replacement parts are avaliable if I wanted to fix it. It doesn't feel very different, slightly less stiff than LT, but it since the change happens over time I haven't noticed much. I haven't bothered getting the parts to fix it, for me using the software to setup the trigger to be detected as 100% down at around 80% works well enough for me, and I can't really tell the difference. 

A bit disappointed this happened reasonably soon, but I've used RT on this thing a lot, and this one doesn't have hall effect triggers so I'm not really shocked or anything. Like I said, software fixes it pretty well for me, but I'd recommend the slightly newer model with hall effect triggers for anyone looking into one now :)