Before the patch I already felt like I was wasting too much time on flight from one place to another, now I haven't even visited DD or any other places in the HB at all as even flying from by base to just outside the map( my base is somewhere over a rock at around 500m height and close to the edge of the map) feels bad with the lower speed and altitude loss.
It didn't use to feel this bad before I leveled up by Exploration , but now it feels like I wasted the missions on that tree. (they're not , as the inventory increase is great all by itself)
Every since this patch I only logged in to do the daily missions on the overland locations as those don't depend on the thopter that much, I haven't rebuild the DD base or did anything else that requires long flights.
Edit: I don't really care about gliding up, just have a good speed while maintaining altitude. I also got the feeling that the max speed is lower now (even when losing altitude) but I haven't glided much to say for sure. Anyway, I'm sure that I'll get used to it in the long term. Except for the speed, I do hope that the max speed wasn't reduced and I was just bad at gliding or it's some temporary issue.