Currently the 5.x branch targets Java 8 as Jakarta EE 9 is the target which works with Java . WildFly has migrated to Jakarta EE 10 which requires a minimum runtime of Java 11. WildFly Arquillian should change it's minimum runtime to Java 11. The main reason for this is being able to use newer version of WildFly Core which also use Java 11.

The target Jakarta EE version will still be 9 as long as Arquillian itself targets Jakarta EE 9. It's only the minimum JVM required will be Java 11.