Document revision id is lesser than sync revision id

Hello,
We are planning to use Couchbase Enterprise for Automatic conflict resolution.

We have set-up Couchbase server, Sync gateway and Java Mobile app as suggested in mobile-travel-sample.

The documents(user flights) are getting synced between WebApp and Mobile App but I see document revision(6-1698b562ae4100000000000002000000) is lesser(number of revisions) than _sync.rev(8-909918ff83faa98369b09b1f6925ae76ccebe89) as mentioned below.

I expect meta.rev should also start with revision 8-some-hash, is it a bug? I need to understand this because conflict resolution depends on revision id.

{
  "meta": {
    "id": "user::rach4",
    "rev": "6-1698b562ae4100000000000002000000",
    "expiration": 0,
    "flags": 33554432,
    "type": "json"
  },
  "xattrs": {
    "_sync": {
      "rev": "8-909918ff83faa98369b09b1f6925ae76ccebe89a",
      "sequence": 107,
      "recent_sequences": [
        101,
        103,
        106,
        107
      ],
      "history": {
        "revs": [
          "3-d5b3d3c8589836d4db03fa071359a51162125f0e",
          "4-da1dc3e3c08246954e101995ac6f4ec186698760",
          "5-7bbd916ef95713a5b12883f8b9880c43dfade5ed",
          "6-ea8fece6c79cff1b2af2ef3f4891f39332fa2705",
          "7-5acadd7ad5147c06285638132fde0db259d67fab",
          "8-909918ff83faa98369b09b1f6925ae76ccebe89a",
          "2-787a754cc7f9b372a16fb7571229db2b",
          "1-92cee5cc23a5989fdd66e8bfc71fdd2f"
        ],
        "parents": [
          6,
          0,
          1,
          2,
          3,
          4,
          7,
          -1
        ],
        "channels": [
          null,
          null,
          null,
          [
            "channel.rach4"
          ],
          null,
          [
            "channel.rach4"
          ],
          [
            "channel.rach4"
          ],
          [
            "channel.rach4"
          ]
        ]
      },
      "channels": {
        "channel.rach4": null
      },
      "access": {
        "rach4": {
          "channel.rach4": 101
        }
      },
      "cas": "0x000041ae62b59816",
      "value_crc32c": "0xee21c1b5",
      "time_saved": "2021-08-06T11:51:40.7288989Z"
    }
  }
}

meta here is server specific and not related to mobile replication, so there is no need to compare the two. I don’t really understand what you mean by the rest of what you said but I will warn that you should treat the revision ID as an opaque object. We make no guarantees about its format and it can change without notice.