Blizzard has made some adjustments to the Overwatch PTR that will change the way the game's heroes move and accelerate. Game director Jeff Kaplan explained in a forum post that the update was originally made to address problems with a couple of specific heroes, but "the changes are systemic" and thus they have an impact on everyone.
"Movement on the ground is much more consistent," Kaplan wrote. "Going up/down inclines will no longer affect the Hero’s speed. Previously, inclines could either make you move slightly faster or slightly slower, depending on the circumstances. Inclines will also no longer cause a small amount of strafing movement when moving diagonally on them."
Interestingly, the changes on the ground have also resulted in better control in the air. "For example, Winston previously was not able to easily make small adjustments to his flight path during his Jump Pack leap, but now he should be able to do that, and it is also noticeable on many of the other Heroes that are often in the air," Kaplan wrote.
Going by the comments in the announcement thread, the overall response seems positive (aside from concerns about Lucio being a little too twitchy for his own good) but Kaplan warned that there could be some unintended side effects, so keep your eyes open. As for patch notes, there are none because a patch wasn't actually required.
