Why can't search user by email?

hi, it’s very confusing for me.

for user 1, I can get it by /users?search=fanguogang%40XXX.com:

[
    {
        "id": 798,
        "name": "范国刚",
        "username": "fanguogang",
        "state": "active",
        "avatar_url": "http://172.25.160.168/uploads/-/system/user/avatar/798/avatar.png",
        "web_url": "http://172.25.160.168/fanguogang",
        "created_at": "2021-09-28T08:58:58.916Z",
        "bio": "",
        "location": "",
        "public_email": "",
        "skype": "",
        "linkedin": "",
        "twitter": "",
        "website_url": "",
        "organization": "",
        "job_title": "",
        "pronouns": "",
        "bot": false,
        "work_information": null,
        "followers": 0,
        "following": 0,
        "local_time": "5:43 PM",
        "last_sign_in_at": "2022-07-13T06:32:41.010Z",
        "confirmed_at": "2021-09-28T12:30:19.884Z",
        "last_activity_on": "2022-08-22",
        "email": "fanguogang@bgzchina.com",
        "theme_id": 1,
        "color_scheme_id": 1,
        "projects_limit": 0,
        "current_sign_in_at": "2022-08-19T09:24:12.139Z",
        "identities": [],
        "can_create_group": false,
        "can_create_project": false,
        "two_factor_enabled": false,
        "external": true,
        "private_profile": false,
        "commit_email": "fanguogang@bgzchina.com",
        "is_admin": false,
        "note": ""
    }
]

but for user 2, get empty array by /users?search=lekejun%40XXX.com, while the response by /users?search=likejun looks like below:

[
    {
        "id": 868,
        "name": "李科君",
        "username": "likejun",
        "state": "active",
        "avatar_url": null,
        "web_url": "http://172.25.160.168/likejun",
        "created_at": "2022-03-03T02:56:21.250Z",
        "bio": "",
        "location": null,
        "public_email": "likejun@bgzchina.com",
        "skype": "",
        "linkedin": "",
        "twitter": "",
        "website_url": "",
        "organization": null,
        "job_title": "",
        "pronouns": null,
        "bot": false,
        "work_information": null,
        "followers": 0,
        "following": 0,
        "local_time": null,
        "last_sign_in_at": "2022-08-13T02:37:12.250Z",
        "confirmed_at": "2022-03-03T02:56:21.029Z",
        "last_activity_on": "2022-08-22",
        "email": "likejun@bgzhina.com",
        "theme_id": 1,
        "color_scheme_id": 1,
        "projects_limit": 0,
        "current_sign_in_at": "2022-08-22T06:37:39.401Z",
        "identities": [],
        "can_create_group": false,
        "can_create_project": false,
        "two_factor_enabled": false,
        "external": true,
        "private_profile": false,
        "commit_email": "likejun@bgzhina.com",
        "is_admin": false,
        "note": ""
    }
]

why ?

the user2’s public_email is updated in database by myself, but still can’t search it by email…