Does anyone have a fix for ianxofour's wither rose farm?

I recently built ianxofour's [wither rose farm](https://www.youtube.com/watch?v=qtXjPaBMMP8) only to find out that the recent update (1.21.6) broke it. It no longer kills any of the snow golems due to a projectile change.

Does anyone know of a way to fix it?