I see the following failure on our Ubuntu 24.04 XWayland headful test system:

StageFocusTest > testStageHasFocusAfterShow(Stage) > [2] javafx.stage.Stage@2bd2b28e FAILED
    org.opentest4j.AssertionFailedError: Stage did not receive the key stroke generated by Robot! This might happen if the Stage did not receive focus after showing. Some tests might fail because of this. Try re-running the tests with '--no-daemon' flag in Gradle. ==> expected: <true> but was: <false>
        at app//org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
        at app//org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
        at app//org.junit.jupiter.api.AssertTrue.failNotTrue(AssertTrue.java:63)
        at app//org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:36)
        at app//org.junit.jupiter.api.Assertions.assertTrue(Assertions.java:214)
        at app//test.robot.javafx.stage.StageFocusTest.testStageHasFocusAfterShow(StageFocusTest.java:218)

I suspect that this is a product bug, not a test bug, but we need to check.