Why loading Hubot account page timeout on browser but I can fetch via API?

$ curl https://github.com/hubot
<html><body><h1>504 Gateway Time-out</h1>
The server didn't respond in time.
</body></html>

$ curl https://api.github.com/users/hubot
{
"login": "hubot",
"id": 480938,
"node_id": "MDQ6VXNlcjQ4MDkzOA==",
"avatar_url": "https://avatars1.githubusercontent.com/u/480938?v=4",
"gravatar_id": "",
"url": "https://api.github.com/users/hubot",
"html_url": "https://github.com/hubot",
"followers_url": "https://api.github.com/users/hubot/followers",
"following_url": "https://api.github.com/users/hubot/following{/other_user}",
"gists_url": "https://api.github.com/users/hubot/gists{/gist_id}",
"starred_url": "https://api.github.com/users/hubot/starred{/owner}{/repo}",
"subscriptions_url": "https://api.github.com/users/hubot/subscriptions",
"organizations_url": "https://api.github.com/users/hubot/orgs",
"repos_url": "https://api.github.com/users/hubot/repos",
"events_url": "https://api.github.com/users/hubot/events{/privacy}",
"received_events_url": "https://api.github.com/users/hubot/received_events",
"type": "User",
"site_admin": true,
"name": "Hubot",
"company": "GitHub",
"blog": "https://hubot.github.com/",
"location": null,
"email": null,
"hireable": null,
"bio": null,
"public_repos": 1,
"public_gists": 0,
"followers": 385,
"following": 0,
"created_at": "2010-11-14T10:29:21Z",
"updated_at": "2020-03-19T19:13:39Z"
}