Can't change code in a function node

[E1cid]

Your node-red is a HA plugin so they have edited it for HA use.

Have you searched the forum as there are some topics about this

Unable to edit function nodes after update (only with Monaco; ace works fine)

This is an old problem. When monaco was first released, we noticed a hand full of contrib nodes were using an old (bad) version of something called multiple-select.js - where the user could not type. You may have one of these node installed.