Unknown Memory's official press release describes the record as "a hybrid of modern experimental music", with the feeling of "Laser sword melancholia" and arrangements of "ominous synth clouds hovering over clinical beats.

[4][6][7] These included The 405 critic Jess Bernard, who called the album "another example of Yung Lean's ability to stunt on a record", with his skills measuring up to those of The Weeknd and Travi$ Scott.

"[13] A critic for The Observer opined that "If Unknown Memory doesn’t quite merit the excited bafflement that initially greeted Lean, its nagging hooks and queasy introspection still make for an intriguing trip",[10] while a Fact reviewer said there was something "beguilingly decadent about Unknown Memory: the way Lean’s confessions of world-weary ennui flow seamlessly into brags about wealth and status; how those dreamy, new-age synth lines play out beneath raps that sound spiritually hollow."

"[8] One negative review of Unknown Memory came from Pitchfork Media's Jonah Bromwich, who felt that the rapper was "doubling down" his personality that made his past work enjoyable to listen to and "simultaneously scrubbing away the most amateurish (and most likeable) parts of his sound.

"[11] He disliked Lean's auto-tuned vocals and "irritating rapping flow", which he felt caused the tracks to be too identical to each other and lost the listeners' interest on the otherwise more "palatable" instrumentals.