Searching a user by handle on its own server produces unrelated results

Performing a user search on a pleroma server, in this case pleroma.site, using a user's handle, in this case @diskette@pleroma.site, produces results completely unrelated to the search.

Example request:

GET /api/v1/accounts/search?q=%40diskette%40pleroma.site HTTP/1.1
Host: pleroma.site
Connection: close
User-Agent: Paw/3.1.8 (Macintosh; OS X/10.14.5) GCDHTTPRequest

Response (truncated for legibility, only showing "username" keys:

[
  {
    "username": "relay"
  },
  {
    "username": "alphakamp"
  },
  {
    "username": "30kfootview"
  },
  {
    "username": "izaro"
  },
  {
    "username": "praveenp"
  },
  {
    "username": "pleromafeed"
  },
  {
    "username": "tarteka"
  },
  ...
]

For comparison sake, performing a similar search on a mastodon server (for example searching @brunoph@mastodon.technology on mastodon.technology) produces a better result:

Request:

GET /api/v1/accounts/search?q=%40brunoph%40mastodon.technology HTTP/1.1
Authorization: Bearer [redacted]
Host: mastodon.technology
Connection: close
User-Agent: Paw/3.1.8 (Macintosh; OS X/10.14.5) GCDHTTPRequest

Response:

[
  {
    "username": "brunoph"
  }
]

I couldn't find anything in the Pleroma docs that suggest this to be expected, so I assume this is a bug.

I also could not find a search query that would return that specific user as the first result on pleroma.