Is brow lift an uneven facial muscles solution?

Perhaps: It is common for one brow to sit lower than the other. This will be much worse if someone has weakness of the facial muscles as in bell's palsy. Certain brow lift operations might be able to improve the symmetry of the brows. Have a consult with a facial plastic surgeon.

No: Botox is a great way to even uneven facial musculature.

We are all uneven: All faces are assymetric and are not made of wood. The brows, especially, are very dynamic structures that constantly change position with different expressions. So, it is impossible to make the brows exactly even with a brow lift. While it may be possible to lessen extreme assymetries, the best results retain the natural normal dynamic assymetry of the face.

Great question: It is difficult to say without seeing photos of what concerns you. If you have two droopy eyebrows with one being more severe than the other, yes a browlift will help. If your eyebrows are in good position but one functions better than the other, potentially Botox to treat the more active side is the best option. Seek a consult with a facial plastic surgeon to fully discuss your options.