I compared logs from kibana 6.5.4 and kibana 6.8.13 ... kibana 6.8.13 logs have lines regarding reindex operations !!!???
{"type":"log","@timestamp":"2021-01-13T11:26:52Z","tags":["debug","upgrade_assistant","reindex_worker"],"pid":17918,"message":"Starting worker..."}
{"type":"log","@timestamp":"2021-01-13T11:26:52Z","tags":["debug","upgrade_assistant","reindex_worker"],"pid":17918,"message":"Polling for reindex operations"}
{"type":"log","@timestamp":"2021-01-13T11:26:52Z","tags":["elasticsearch","query","debug","admin"],"pid":17918,"message":"200\nPUT /_template/.management-beats?include_type_name=true\n{\"index_patterns\":[\".management-beats\"],\"version\":67000,\"settings\":{\"index\":{\"number_of_shards\":1,\"auto_expand_replicas\":\"0-1\",\"codec\":\"best_compression\"}},\"mappings\":{\"_doc\":{\"dynamic\":\"strict\",\"properties\":{\"type\":{\"type\":\"keyword\"},\"configuration_block\":{\"properties\":{\"id\":{\"type\":\"keyword\"},\"type\":{\"type\":\"keyword\"},\"tag\":{\"type\":\"keyword\"},\"description\":{\"type\":\"text\"},\"config\":{\"type\":\"keyword\"},\"last_updated\":{\"type\":\"date\"}}},\"enrollment_token\":{\"properties\":{\"token\":{\"type\":\"keyword\"},\"expires_on\":{\"type\":\"date\"}}},\"tag\":{\"properties\":{\"id\":{\"type\":\"keyword\"},\"name\":{\"type\":\"keyword\"},\"color\":{\"type\":\"keyword\"},\"hasConfigurationBlocksTypes\":{\"type\":\"keyword\"}}},\"beat\":{\"properties\":{\"id\":{\"type\":\"keyword\"},\"status\":{\"properties\":{\"type\":{\"type\":\"keyword\"},\"timestamp\":{\"type\":\"date\"},\"event\":{\"properties\":{\"type\":{\"type\":\"keyword\"},\"message\":{\"type\":\"text\"},\"uuid\":{\"type\":\"keyword\"}}}}},\"active\":{\"type\":\"boolean\"},\"last_checkin\":{\"type\":\"date\"},\"enrollment_token\":{\"type\":\"keyword\"},\"access_token\":{\"type\":\"keyword\"},\"verified_on\":{\"type\":\"date\"},\"type\":{\"type\":\"keyword\"},\"version\":{\"type\":\"keyword\"},\"host_ip\":{\"type\":\"ip\"},\"host_name\":{\"type\":\"keyword\"},\"ephemeral_id\":{\"type\":\"keyword\"},\"tags\":{\"type\":\"keyword\"},\"metadata\":{\"dynamic\":\"true\",\"type\":\"object\"},\"name\":{\"type\":\"keyword\"}}}}}}}"}