[9] On December 19, 2018, it was announced that Haechan had fractured his shin bone while preparing for the Neo City – The Origin tour (2019–2020) and would be taking a hiatus from group activities to recover.

[14][15] At the Neo City – The Link tour (2021–2022), Haechan and fellow member Taeil performed an unreleased R&B track titled "Love Sign", which they composed with producer Deez [ko].

[17] Haechan recorded a remake of the 2001 Toy song "Good Person" for the soundtrack of the Playlist Studio web drama Ply Friends: Seoyeon University Class of '22 for release on March 6, 2022.

[20] Haechan stated that his mother greatly influenced his music taste by introducing him to songs such as "Billie Jean" by Michael Jackson, whom he has cited in multiple interviews as one of his role models and the reason he wanted to pursue a singing career.

[21][22][11] Haechan also named labelmate Taemin of Shinee as a major influence, crediting his group's debut single "Replay" with inspiring him to become an idol and audition for SM Entertainment.

[27] In August 2023, he donated ₩50 million to the Korean Red Cross to support the victims and areas affected by the wildfires that broke out that month on the island of Maui, Hawaii.