As per Feign Death and capping flag
Hunters can camo to a flag, feign death, and interact with the flag all without showing a nameplate, or canceling feign death.
AoE abilities do not appear to break the cap either. knocks like typhoon or incapacitating roar etc will break the cap
This is happening at all ratings from 1800 all the way up to 2./2.5k.
Of course, by using other addons like Battleground enemies, or constantly scanning the ground for a random dead body, you can counter this but its not something that is intended.
expected behaviour would be for feign death to break when interacting with objects as with other forms of immune capping that have been removed