Cosmetic Thaumaturge's Plasma Blast Effect crashes my friends games on every use

We have been getting a TON of crashes in the Interlude and onwards, and we finally figured out why.

The cosmetic "Thaumaturge's Plasma Blast Effect" crashes my friends computers on EVERY use now. Reliably 100% of the time.
When the cosmetic is not equipped, everything is fine.
As soon as I equip it and charge plasma blast, they crash IMMEDIATELY. No error, straight to desktop.

I used to crash as well, but now it is only crashing them reliably.