Taking Life Damage Despite Full ES and Immunities: Bug or Hidden Mechanic?

Hi everyone, I’ve recently started playing Path of Exile 2, so I’m not a veteran player of the first game. I’m still learning the mechanics, but I’ve encountered a strange situation that I can’t explain.

As you can see in the attached image https://ibb.co/98mL2Sy

My Energy Shield is completely full (over 21k).
My Mana is full as well.
I am immune to Chaos Damage.
I have a Charm equipped that provides immunity to Bleeding, and is full.
Despite all these defenses, I took direct Life damage, killed by 3 normal tiny mobs during a breach. I’m struggling to understand what caused this.

I’ve double-checked that there were no degen effects or mechanics bypassing Energy Shield and Mana.
The anti-bleeding Charm seems to function correctly, so I don’t think Bleeding was the issue.
As a new player, I’m wondering: Is there any damage type or hidden mechanic that can bypass these defenses? Or could this be a bug?

Any help or explanation would be greatly appreciated! Thanks in advance.