Hi, it was only in the past week or so. Definitely since the update, as I play almost every night.
I only noticed because I was recording some videos of my runs for YouTube. I was only Prestige 25 at the time of recording, but I managed to complete some runs in around 6:01, 06:39, and 6:58. My speed was only at x1.8, with a strength around x22.
But now I am Prestige 40; my speed is around x2.0/x2.1, and my strength is around x28, yet I am sometimes taking longer than the above-stated times, and that is with NPCs turned off and with me just running through without healing or collecting any pickups/mutagens.
I mainly only use the myst guantlets, so whether it has anything to do with those, I don't know. But it definitely feels a lot slower than before;
I remember thinking before, when I was a lower level, that even at x1.8 the speed felt a bit too fast to control, and I kept running into doors and objects, but you get used to it after a while. But now, it just feels very sluggish whilst sprinting.
One other thing you might like to know (I guess likely how the device or Verse works; you probably have no control over it, as it's a shared client I guess in coop) - but if I have NPC set to off and a player on a run has them set to on, then they always appear (I can even rescue them, with the setting being off) - but if I am on a pure solo run with this off, it works as expected; none appear.
Hope this helps; let me know if you need any other info.
Kind regards,