Grace played part of a Garageband production of the song, live on Instagram in April 2020. This is how she presented the song then:
"Uhh – yo, this one! (laughing), bro – I don’t even know, if I should play this one. I am getting goosebumps even thinking about this, ‘cause it’s like, half of me is like – maybe I should keep it as a surprise – you know what, there is only about 1900 people watching this, and I doubt a ton of people are recording and the people who are, are probably just going to post it once, it’s not going to go viral or anything, I am not Ariana Grande. Are you all listening close? Listen close! [Plays the song] I literally can’t breathe, dude it’s so good … this song is so freakin good, its like so punk, and I have never made a song like that before, and I am telling you!!! (Grace on IG live, April 15, 2020 – Performance 361)
In an interview with Ladygunn Magazine, she later told the genesis of the song like this: "I wish that I would have had a reality show camera, because it was the coolest process that felt so good,” she says of writing the track with producer Mike Elizondo. “It was after a really long day, we were so tired and over it, we had been writing stupid ballads all day that were just turning into nothing. And he picks up the bass and starts playing that baseline and it was literally like a movie. I grabbed this microphone that was plugged into Logic and started riffing on the lyrics, and we were like, ‘Wow, that’s a really good song.’ And then we literally just wrote it and recorded it."
Despite the bass-heavy track and the fact that Vanderwaal wields a bass guitar in her music video for her previous single, “Don’t Assume What You Don’t Know”, she admits that she doesn’t actually know how to play the instrument. “I’m happy that I was believable, but I don’t know how to play the bass,” she says. “Myth shattered.”
This first sneak peak of the song was later muted by the copyright holders (Sony) in the run-up to the release of the song. The early peak had much simpler production than the final version, which added a more instrumentation, voice-overlays and effects. In her IG live up to the release of te song Grace explained that the idea for the song came in a writing sessionwhen someone played the bass patern which features prominently in the song. The song then grew from that.
"VanderWaal originally wrote its lyrics, which tell the story of a young person navigating the industry in Hollywood, as part of a writing session over a year ago. It was put on the back burner at first, but VanderWaal knew it was something special — after all, it was a topic she knew well. The song is all about the fantasies of Hollywood and how I’ve personally witnessed the debunking of all those myths. People put fame and beauty on such a pedestal, as if that’s the answer to life and all of that. I want people to take away [from the song] that your life is awesome, and my life is awesome, and everyone just makes the best of what they have and can find their happy shit in their own shit.” (Interview with Lauren Mccarthy for Nylon March 4, 2021)
"It’s as much a statement as it is entertainment. ... VanderWaal steps up her game in a huge way. Her voice comes at you with attitude, swagger, and full of confidence. Her words are sharpened to a point and will not be dismissed. ... It shows the world the girl can rock." (Review in The Indiespot March 5, 2021)
"'Don't Assume What You Don't Know' starts softly enough but it isn't long before the power chords kick in and Grace lets her vocal break free as she finds her range. The arrangement works well for VanderWaal as the track flits between the stripped back and delicate to a full blown heavy Pop-Rock. On the evidence of her latest track I think that Grace VanderWaal has done a brilliant job of re-inventing herself with a very credible, deftly conceived track to launch a fresh start." (contactmusic.com March 10, 2021)