Hi, is

enableFeaturePreview("GRADLE_METADATA")

still needed for Multiplatform projects on Gradle 5.3.1, where gradle metadata is stable?

However, Gradle 5.3 will not automatically publish it by default — that will come in 6.0. You can publish Gradle Module Metadata today, but you have to opt into its publication by using either the Maven Publish or Ivy Publish plugins and enabling the experimental publishing feature by adding the following line to your settings script:

settings.gradle(.kts)

enableFeaturePreview("GRADLE_METADATA")

Seems from Gradle 6 and higher: https://blog.gradle.org/gradle-metadata-1.0

Yes, it's still needed. If you don't add it, Gradle 5.3+ will read the module metadata when resolving dependencies but won't write it during publishing.

So it’s still needed for libraries but it’s no longer needed for apps, right?

Yes.