As a healer main, seeing this happen makes me cringe. It basically boils down to the White Mages not doing their job correctly because they were tunnel visioning their single button smashing.

It’s not just a thing in Bardam’s as mentioned above; any tank that’s leveling in dungeons that are relevant to its level enough to not need syncing are going to have the defense of wet paper compared to being overgeared and downscaled. Add to this the fact that Dark Knight in particular does not have very many defensive tools outside of role skills at that level, while White Mage has none to provide the tank at all compared to Sage and Scholar.

Any healer worth their salt will look at the tank’s level upon spawning in a leveling dungeon, realize that the tank will likely take more damage than they would had they been overgeared, and adjust their expectations of balance between DPS and healing. Anybody else is either not a good healer (yet?), or they’re taking the “dps is the only metric and if you so much as use a GCD heal you’re garbage” mentality that’s built up over the years far too seriously.

From the sounds of it you’re doing fine, so don’t worry about it.