Simplifying Symbolics.jl expression

[greatpet]

@Alseidon

julia> (a^2 + b^2) * cos(c + d) * e * f + e * cos(c + d) * (-a^2 - b^2) * f |> simplify
(a^2 + b^2)*e*f*cos(c + d) + (-(a^2) - (b^2))*e*f*cos(c + d)

Just change simplify to expand, and the output becomes 0.
It’ll be great to have a smarter simplify, but in this case, expansion is clearly the solution.