No it's not very hepatotoxic, on the contrary.

"Hydroxychloroquine has not been associated with significant serum enzyme elevations during therapy of rheumatologic diseases. Furthermore, clinically apparent liver injury from hydroxychloroquine is rare. " https://www.ncbi.nlm.nih.gov/books/NBK548738/

"Despite use for more than 50 years, chloroquine has rarely been linked to serum aminotransferase elevations or to clinically apparent acute liver injury."https://www.ncbi.nlm.nih.gov/books/NBK548224/