I have created an automation that runs a custom script after a record is updated. In the script I would like to perform different operations depending on the overwritten values. Is there any way to access those values from the script? (Similar to how one would use OLD in a SQL trigger).
Scripting has no access to the previous value of a field. You have to design a system to hold the previous value in a different cell. This also typically means that users cannot directly edit the field directly in the grid view. Instead have a script or automation that copies the old value into a different field, and then puts the new value in the original field. Then the script reads the “old value” field to see what the old value is.