When I preview my (quite large) diagram, I get this:

Edge limit exceeded. 500 edges found, but the limit is 500.

Initialize mermaid with maxEdges set to a higher number to allow more edges.
You cannot set this config via configuration inside the diagram as it is a secure config.
You have to call mermaid.initialize.

I changed Mermaid › Vscode: Max Edges setting from 1000 to 10000 and restarted VSCode, but it had no effect.