In 10.18 "Use custom repositories" is a Studio preference: https://docs.mendix.com/refguide/managed-dependencies/#custom-repos
Setting it requires extra work for new team members. I don't think it's even required in Studio because this can be set in a file in Gradle home. Traditionally, in Maven and Gradle custom repos were set in the project file.
I propose to move this to the Dependencies tab of the App settings.