I tried to run it like, hoping that it would use SDL3, but the cursor is still large.
`LD_LIBRARY_PATH=/usr/lib/libSDL3.so.0.1.6:$LD_LIBRARY_PATH ./factorio`

I have the same issue on Hyprland. You say the issue is fixed on SDL3, but how can I change the SDL used for the factorio?
I used Lutris to install, so I think it's not that hard to do it.