Yes, I've found that when you attack a hoglin in the safe zone, the attacked hoglin will remain passive, but any other hoglins will attack the player, even in the safe zone.
I can no longer reproduce this bug in snapshot 20w18a.
Hardcore player biting the dust: https://clips.twitch.tv/GoldenGleamingChipmunkWholeWheat
Upon further testing, I've discovered that if you load a hardcore world that was last saved in the nether, regardless of whether cheats were used, your hardcore hearts will be removed. Interestingly if you re-load the game after saving in the overworld, your hardcore hearts will re-appear.
I've recreated this both on my computer, a Twitch Streamer's computer, and all of the current bug reports with screenshots regarding this bug happened when the user was in the Nether.
The reason I initially suspected some combination of "cheaty" commands is because I was attempting to do a Nether-start.
I've noticed that if you use commands at any point by opening to LAN and enabling cheats the hearts will turn to normal survival hearts upon re-logging. I'm not sure if this is intentional but I don't like it. For example hardcore players using cheats to place themselves in the nether for a nether only run will lose their hardcore hearts.
The only thing that should cause a hardcore player to lose their hardcore hearts is a death.
I believe the following ticket is a duplicate of this one, with more information about the behaviour: MC-180111