The current Overwatch PTR has a lot going on. Obviously there's Doomfist, the new rocket-punching melee hero. Then there's the changes to Loot Boxes and the new Highlight system. Now, there's a slate of hero balance changes too.
First and foremost, the Russian weightlifter Zarya is receiving a big buff to her ultimate ability, Graviton Surge. In addition to sucking in and trapping all enemies caught in the vortex, Graviton now also disables all movement abilities of affected targets, similar to how Junkrat's trap affects abilities.
Previously, getting caught in a Grav was only really problematic for some of the Overwatch roster, as many heroes had abilities—Reinhardt's Charge, Genji's Swift Strike, or D.Va's Boosters, for example—they could use to escape the black hole. After this change, any hero caught in Zarya's ult should expect to be stuck there the whole time.
The next change is for Reinhardt: the swing speed of his Hammer has been increased by roughly 10 percent, alongside a number of other small tweaks designed to make it feel a lot better to swing and make contact with enemies. Secondly, Reinhardt's Charge has been tweaked so that impacting another charging hero (such as Doomfist or an enemy Reinhardt) no longer deals damage to both characters. Both heroes are still knocked down from the head-on collision, but they won't be hurting from the impact.
Speaking of Doomfist, his signature Rocket Punch has also had its total travel distance reduced. At full charge, it now travels about 21 meters, down from around 30 at launch. Blizzard has also added a UI indicator to Seismic Slam that shows how much damage the ability will deal, and when using the ability in mid-air, targeting is now restricted to locations lower than Doomfist's current height.
Finally, McCree and Reaper received two small tweaks. McCree's Flashbang now slows targets significantly when they are stunned, making them "less likely to slide away around a corner or something similar once they are stunned." I wasn't aware this "sliding away" was really an issue, as Flashbang's stun should root you in place, but a slow (during the stun, not after, to be clear) has been added either way. As for Reaper, the audio cues of his Shadow Step ability have been dramatically reduced—a change that will make it easier for him to surprise enemies with a flanking attack.
As always, balance updates on the Overwatch PTR are subject to change. For more information, check out the official PTR patch notes.