L-2021 is in the library.
Some monitors produced by LG have a type-c port. If the monitor has a type-c port, then it is not produced by AOC. All monitors in the library are produced by AOC.  L-2021 is either in the library or has a type-c port. L-2021 is either produced by AOC and produced by LG, or neither produced by AOC nor produced by LG.
∃x (LG(x) ∧ TypeC(x)) ∀x (TypeC(x) → ¬AOC(x)) ∀x (Library(x) → AOC(x)) Library(l-2021) ⊕ TypeC(l-2021)  ¬(AOC(l-2021) ⊕ LG(l-2021))