A friend and I have both noticed this effect over a long period of time, so it’s not new for us. I think it is probably wider spread.
If you ground an opponent, they seem to take only “white” hits while on the ground.
As an Ogryn; I can knock an opponent over with a ripper blast. But while they’re on the ground, the damage from another barrage often does little to no damage.
I’ll try and record some examples. But a flamer just took 4 triple-rounds from a ripper. One to knock them over, then 2 on the ground (central mass). Then one as it got up.
I got hit markers on all 4. But only whites.
I’ve noticed this on vet/zealot shotguns as well, where once staggered/knocked over, you don’t seem to do any real damage while an enemy is floored.