When the down and the up event arrive in rapid succession, it is possible that the onPress callback is executed after the onTap callback.

It is currently not possible to reproduce this in a test, because we use an UnconfinedTestDispatcher. When we switch to a StandardTestDispatcher, the following test (when added to TapGestureDetectorTest.kt) will fail:

@Test
fun testOrderOfExecution() {
    val events = mutableListOf<String>()
    rule.setContent(
        layoutWithGestureDetector {
            detectTapGestures(
                onPress = { events.add("onPress") },
                onTap = { events.add("onTap") }
            )
        }
    )
    rule.onNodeWithTag(TargetTag).performTouchInput {
        down(center)
        up()
    }
    rule.waitForIdle()
    assert(events.size == 2) { "should have received 2 events, but received $events" }
    assert(events[0] == "onPress") { "first event should be onPress, but events were $events"}
    assert(events[1] == "onTap") { "second event should be onTap, but events were $events"}
}

While very difficult, I think you could reproduce it in a demo app with an incredibly short tap.