Thanks for the clarification

The airfield owner or operator typically requests such a change.

This seems a strange response being that my question was more generic and I had cited EGTR as an example. Back to my original question and perhaps let me rephrase: What dictates Circuit diagrams being depicted and then to subsequently be removed? Happy to raise a support ticket with regards the specific example of EGTR

You would need to contact customer support to enquire about a specific airfield's update history. They might be able to give you an answer but I certainly can't.

Why do circuit diagrams at certain airfields keep appearing and disappearing in chart updates? Elstree EGTR being an example where every now and then, the circuit diagram will appear following a chart update only to be removed the following chart update. Why would this keep happening?