He will not ride the Vuelta.
This article says he's been battling unspecified viral infection since the Giro.
https://www.pulzo.com/deportes/equipo-mitchelton-deja-esteban-chaves-vuelta-espana-PP533683
Edit: It also says that he keeps training and, for now, he has not been pulled from other races of the 2nd part of the season.
All that according to his father.
This article says he's been battling unspecified viral infection since the Giro.
https://www.pulzo.com/deportes/equipo-mitchelton-deja-esteban-chaves-vuelta-espana-PP533683
Edit: It also says that he keeps training and, for now, he has not been pulled from other races of the 2nd part of the season.
All that according to his father.