The actual conclusion is simply that there's no evidence to support that they work (or don't work). Which isn't exactly a ringing endorsement given that it's hard to prove a negative.

"It would be accurate to say that the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses, and that the results were inconclusive. Given the limitations in the primary evidence, the review is not able to address the question of whether mask-wearing itself reduces people's risk of contracting or spreading respiratory viruses."