This reproduces locally. https://github.com/elastic/elasticsearch/pull/84418 recently touched this area so perhaps it's related,

**Build scan:**
https://gradle-enterprise.elastic.co/s/yfdjcrugjoaju/tests/:server:test/org.elasticsearch.cluster.routing.DelayedAllocationServiceTests/testDelayedUnassignedScheduleRerouteRescheduledOnShorterDelay

**Reproduction line:**
`./gradlew ':server:test' --tests "org.elasticsearch.cluster.routing.DelayedAllocationServiceTests.testDelayedUnassignedScheduleRerouteRescheduledOnShorterDelay" -Dtests.seed=F4B6841BDF04C52E -Dtests.locale=ca -Dtests.timezone=Asia/Aden -Druntime.java=17`

**Applicable branches:**
master

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.cluster.routing.DelayedAllocationServiceTests&tests.test=testDelayedUnassignedScheduleRerouteRescheduledOnShorterDelay

**Failure excerpt:**
```
java.lang.AssertionError: Values should be different. Actual: org.elasticsearch.cluster.routing.DelayedAllocationService$DelayedRerouteTask@305ac796

  at __randomizedtesting.SeedInfo.seed([F4B6841BDF04C52E:D96C68645E00C8A9]:0)
  at org.junit.Assert.fail(Assert.java:88)
  at org.junit.Assert.failEquals(Assert.java:185)
  at org.junit.Assert.assertNotEquals(Assert.java:161)
  at org.junit.Assert.assertNotEquals(Assert.java:175)
  at org.elasticsearch.cluster.routing.DelayedAllocationServiceTests.testDelayedUnassignedScheduleRerouteRescheduledOnShorterDelay(DelayedAllocationServiceTests.java:521)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:568)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:833)

```
server/src/test/java/org/elasticsearch/cluster/routing/DelayedAllocationServiceTests.java
.build();
        final long baseTimestampNanos = System.nanoTime();
        allocationService.setNanoTimeOverride(baseTimestampNanos);
        clusterState = allocationService.reroute(clusterState, "reroute");
        
        clusterState = startInitializingShardsAndReroute(allocationService, clusterState);
        
        clusterState = startInitializingShardsAndReroute(allocationService, clusterState);
        assertFalse("no shards should be unassigned", clusterState.getRoutingNodes().unassigned().size() > 0);
        String nodeId = null;
        final List<ShardRouting> allShards = clusterState.getRoutingTable().allShards("test");
        
        for (ShardRouting shardRouting : allShards) {
            if (shardRouting.primary() == false) {
                nodeId = shardRouting.currentNodeId();
                break;
            }
        }
        assertNotNull(nodeId);
        
        clusterState = stateWithoutNodeId(clusterState, nodeId);
        clusterState = allocationService.disassociateDeadNodes(clusterState, true, "reroute");
        ClusterState stateWithDelayedShard = clusterState;
        
        assertEquals(1, UnassignedInfo.getNumberOfDelayedUnassigned(stateWithDelayedShard));
        ShardRouting delayedShard = stateWithDelayedShard.getRoutingNodes().unassigned().iterator().next();
        assertEquals(baseTimestampNanos, delayedShard.unassignedInfo().getUnassignedTimeInNanos());
        
        CountDownLatch latch = new CountDownLatch(1);
        AtomicReference<ClusterStateUpdateTask> clusterStateUpdateTask = new AtomicReference<>();