Movement is a character controller I control completely manually, I agree that the falloff is quite harsh and I'll keep it in mind that it needs a few tweaks!
I noticed the stutter with the fire, but couldn't find a fix (outside of the github issue saying it would be fixed in future versions) I will look into fixing that though. Seems to work fine in the editor.
Having a blast with godot after I stopped using a certain other engine! :)