IndieWire:

Jeremy Renner has starred in huge action movies such as “The Avengers," “Avengers: Age of Ultron," and “The Bourne Legacy," but it wasn’t until he decided to star in the comedy film “Tag" that he ended up with two broken arms. The actor made headlines in July 2017 when he revealed both of his arms broke during a stunt gone wrong during production on the comedy film, but it turns out the shoot wasn’t affected too much by the injury. According to Jon Hamm, the film relied on CGI to replace Renner’s arm casts with human skin.

I really hope this CG is Henry Cavill’s-Upper-Lip-in-Justice-League level bad.