- JVM IR backend promoted to beta, enabled by default for Kotlin 1.5, with added no‑arg plugin support, inline class constants, and improved Java annotation handling.
- Preview of language version 1.5 features including sealed interfaces (IDE integration, inspection, intention) and Xjvm preview, plus a new language version selector in the compiler configuration.
- Extensive bug fixes across JVM, JS, Native, IDE, Gradle, Kapt, incremental compilation, and tooling addressing annotation loading, type‑alias recursion, Kotlin/JS vararg spread, and build stability.