I cannot get the correct user

[b11p]

Hello, when I am querying user Death XD_old (user id: 8955597), I get death_xd (user id: 16209767).
The URL I used is https://osu.ppy.sh/api/get_user?k=[key]&u=Death+xd_old.
The response is

[{"user_id":"16209767","username":"death_xd","join_date":"2020-02-16 15:51:46","count300":null,"count100":null,"count50":null,"playcount":null,"ranked_score":null,"total_score":null,"pp_rank":null,"level":null,"pp_raw":null,"accuracy":null,"count_rank_ss":null,"count_rank_ssh":null,"count_rank_s":null,"count_rank_sh":null,"count_rank_a":null,"country":"IN","total_seconds_played":null,"pp_country_rank":null,"events":[]}]

[tybug]

This is intentional for *_old usernames: #280 (comment)