One of my Elasticsearch nodes stopped the service and moved the master to another node.
The logs do not show much info, why but rather just say master moved to a different node.
[2021-11-23T13:57:21,216][INFO ][o.e.n.Node ] [s32.mydomain.local] initialized
[2021-11-23T13:57:21,217][INFO ][o.e.n.Node ] [s32.mydomain.local] starting ...
[2021-11-23T13:57:21,378][INFO ][o.e.x.s.c.PersistentCache] [s32.mydomain.local] persistent cache index loaded
[2021-11-23T13:57:21,482][INFO ][o.e.t.TransportService ] [s32.mydomain.local] publish_address {10.1.9.132:9300}, bound_addresses {[::]:9300}
[2021-11-23T13:57:25,160][INFO ][o.e.b.BootstrapChecks ] [s32.mydomain.local] bound or publishing to a non-loopback address, enforcing bootstrap checks
[2021-11-23T13:57:25,180][INFO ][o.e.c.c.Coordinator ] [s32.mydomain.local] cluster UUID [OWJKtACaQKekQyQdMKZ0hw]
[2021-11-23T13:57:25,708][INFO ][o.e.c.s.ClusterApplierService] [s32.mydomain.local] master node changed {previous , current [{s34.mydomain.local}{J0a50UUERau7eS8RNye1EA}{yi4J1_P7QMSic0DkXPIvaQ}{10.1.9.134}{10.1.9.134:9300}{lmr}{ml.machine_memory=12428423168, ml.max_open_jobs=20, xpack.installed=true, ml.max_jvm_size=4294967296, transform.node=false}]}, added {{s34.mydomain.local}{J0a50UUERau7eS8RNye1EA}{yi4J1_P7QMSic0DkXPIvaQ}{10.1.9.134}{10.1.9.134:9300}{lmr}{ml.machine_memory=12428423168, ml.max_open_jobs=20, xpack.installed=true, ml.max_jvm_size=4294967296, transform.node=false},{s33.mydomain.local}{c9UZRp6fTJWh5gtD2jaglg}{GQow_82xTiWJtcxgGzP42g}{10.1.9.133}{10.1.9.133:9300}{cdfhilmrstw}{ml.machine_memory=16654835712, ml.max_open_jobs=20, xpack.installed=true, ml.max_jvm_size=10737418240, transform.node=true}}, term: 23, version: 68964, reason: ApplyCommitRequest{term=23, version=68964, sourceNode={s34.mydomain.local}{J0a50UUERau7eS8RNye1EA}{yi4J1_P7QMSic0DkXPIvaQ}{10.1.9.134}{10.1.9.134:9300}{lmr}{ml.machine_memory=12428423168, ml.max_open_jobs=20, xpack.installed=true, ml.max_jvm_size=4294967296, transform.node=false}}