Win rate of each changed hero before and after the update, on every match played. The noise threshold, the largest swing among the 32 heroes this patch did not touch, is 5.64 points.
Mo & Krill (buff): 51.42% → 46.8% win rate, -4.62 points, within the noise
Yamato (change): 49.66% → 45.04% win rate, -4.62 points, within the noise
Silver (change): 47.24% → 43.48% win rate, -3.76 points, within the noise
Celeste (change): 49.18% → 48.13% win rate, -1.05 points, within the noise
Rem (change): 46.43% → 45.82% win rate, -0.61 points, within the noise
Graves (change): 57.26% → 56.84% win rate, -0.42 points, within the noise
Every change in this update
Health pickups (medic troopers, floating health orbs): their regeneration is now flagged as a positive effect (not in the announcement) (bugfix)
Damage summary: the hint now says to hold Extra Info to see modified stats (not in the announcement) (bugfix)
The Broker is gone: the corrupted item shop is disabled, as City Never Sleeps announced for the arrival of the first new hero (not in the announcement) (change)
New ping: pinging a low-health teammate offers them a heal, if they are within 2,500 units and in line of sight (not in the announcement) (change)
Settings: choose whether the menu opens on your current hero or on your base settings, and whether it remembers the hero you last selected (not in the announcement) (change)
Celeste — In-game role changed from Marksman to Mystic (not in the announcement) (change)
Graves — In-game role changed from Marksman to Mystic (not in the announcement) (change)
Mo & Krill — The "Digging..." tunnel channel no longer gets longer with duration bonuses (not in the announcement) (buff)
Rat King — New hero: Rat King is now playable (Scrap Grenade, Swarm of Rats, Royal Pestments, Banner of Rattania) (change)
Rem — Now has an in-game role: Mystic (not in the announcement) (change)
Silver — In-game role changed from Marksman to Brawler (not in the announcement) (change)
Yamato — Flying Strike: its valid targets are now listed explicitly (heroes, troopers, bosses, objectives, summons, neutrals), which likely leaves out the new critters (not in the announcement) (change)
Ballistic Enchantment — Technical change: no damage type is excluded any more from triggering its bonus (not in the announcement) (change)
Bugs (1-soul critters around the map): respawn every 15s instead of 30s, and 1 in 10 is now a faster rat (not in the announcement) (change)
Neutral monsters: their shots now have a small aiming spread (0 to 3) (not in the announcement) (change)