Cannot assign a new value to a constant.

[slender isle]

if that script is assigned to your progress bar, i believe to set the value of a progress bar it is just "value = paranoia_value"

value is a property on ProgressBar, so it is ProgressBar.value, but since you are on the progress bar, I believe it is just "self.value" or "value"

[pastel umbra]

var paranoia_value = GlobalVariables.paranoia

You only copy once at load time so it will never tick, you must read it continiously, not store it

extends ProgressBar

func _process(_delta):
    value = GlobalVariables.paranoia

No worries lol