Hi @koliron, welcome to the Glitch forum!
It looks to me like you might actually be getting quick.db version 7.0.0-b22 instead of 7.0.0-b21 - when I spin up a new project with that package.json dependency that’s what I get, which is consistent with the semantics of “^” in package versions (it’s a little arcane to me, and you can read more about it at https://docs.npmjs.com/misc/semver, but as I read it “^” in this case means “allow any version that’s in the 7.x family”).
When I do a console.log(db) after requireing that package, I get a version of 7.0.0b22 and indeed it seems like that version doesn’t export a startsWith function, while 7.0.0b21 does. If you remove the “^” from the beginning of the quick.db version specifier I think your current code will work, but it seems as though that function is being deprecated and I’d probably find a different solution to that instead.