I just got called a griefer whilst playing Frost in 2025. Please help me understand how that makes sense?

The year was 2025. The mission Mausoleum East, The Steel Path.

My build, Frost Prime and Icy Avalanche, Biting Frost. Rocking a Tenet Glaxion, Epitaph Prime, Sibear and Nautilus Prime and Verglas Prime.

I'm in the mission, tanking 96% of the damage like boss. Slaying out like the enemy is made of cheese and I'm the oven. Then some random DMs me that I'm a griefer and hits Ignore before I can ask:

How?