V6:
I was driving through the desert and explodey zombies were exploding left and right, like 5 in 30 seconds sometimes, sort of like they spawned in severely damaged (I didn't get a chance to see if that was the case, though). There were some that didn't explode, but they kind of seemed to be a minority (POI spawns behaved normally and first exploded when damaged).
Pretty funny, but probably not intended.
I haven't had the same thing happen in the forest biome (haven't been to snow or wasteland yet).
(Edit: It does happen in forest too, I think it just happens a lot less because fewer explodey ones spawn there).
In the last testing video, Khaine said there was a bug with zombie health. I think it was double what it should have been or such. Did the same bug cause Scavenger difficulty to have less health than intended?
I started my game on Scavenger as I always do, but it was far easier than it's been in previous DFs. I one-shot almost everything with level 1 stone spear and primitive bow and at day 20 a compound crossbow and an M4A1 one-shot absolutely everything, no matter where I hit them.
On day 8 or so I ran into a surprise radiated feral wight in an otherwise low stakes POI and it died almost instantly to my scrap spear and level 6 advanced pistol.
Though, in 20 days I didn't see a single feral or rad at night nor in wandering hordes, so it's not just health that's different (I don't know if health might affect whether a zombie can spawn as a rad or feral).
Then I changed the difficulty to the next step up (default) and suddenly wandering hordes are like 30-50% ferals with lots more health (in the forest biome), so that's quite a difficulty spike.