Can the drug hydroxycholoroquine also cause color blindness?

Yes: Hydroxychloroquine can rarely cause damage to the part of the eye where the majority of color sensing cells reside. This is why it is important to check the eye's health with a visual field test on an annual basis using a red dot of light as the test stimulus to see if you can see it on a white screen.

Yes 1st sign: When used in high doses as in treatment of malaria vision damage is frequent but in doses for lupus etc this is rare but color vision loss can be an early sign well before visual acuity damage. Reversal of damage can occur if stopped early.