In a whopping 8 GB download available right now for the Public Test Region (PTR), Overwatch has made changes to 13 heroes in a patch dubbed a "remaster".
This year, Overwatch has seen some of the biggest changes since release, with the introduction of role queue and new tank hero, Sigma. But bringing in such a strong shield tank has disrupted the game's meta, and a lot of the new hero updates have seemed designed to combat it.
Sigma is the most affected with the changes. His Kinetic Grasp ability (which allows him to absorb enemy damage and turn it into shields) no longer blocks Roadhog's Chain Hook or Brigitte's Whip Shot, making him susceptible to their interruptions. Sigma's ultimate, Gravitic Flux, will only hold players in the air for 0.9 seconds, reduced from 1.2 seconds.
Perhaps the biggest change for the tank hero however, is to his Experimental Barrier. The regeneration rate for it has been reduced from 175 to 150 per second, and there's now a one second cooldown after recalling it, stopping players from spamming the shield and encouraging them to use it more strategically. The barrier's initial 0.2 second cast time has also been removed. On their own, these changes aren't huge, but paired with some of the buffs detailed below he becomes a much more manageable tank to take down due to the risks he'll have to take to effectively use these abilities.
Orisa's Protective Barrier cooldown is increased, Symettra's Photon Barrier duration and health is reduced, and Baptiste's Immortality Field health is decreased - all nerfs to protective abilities.
Where the buffs are concerned, Tracer's pistol damage falloff now starts at 13 meters, up from 10, heavily increasing the damage she can do at range (as demonstrated by u/THE-WALRUS-KING below).
D.va's Defense Matrix has been buffed, as has Winston's barrier and Lucio's speed boost effects - all changes which could help see a return of the long-reigning dive meta (a comp which had its own problems back in 2017).
Moira, Doomfist, Sombra, Roadhog and Mercy bring up the last of heroes to receive updates, all of which you can read in detail in the patch notes.