Since it's a reflection from the bathroom mirror, and reflections have been used a lot in art to provide commentary and especially to reveal how the "subject" sees themselves, I'm guessing that's the case here.

That also gels with the overall them. Having to take medicines constantly to be able to function can certainly make you feel like a prisoner and the drugs themselves can make you feel like you're in an emotional prison.

Perhaps the picture is just a normal self portrait, but the subject, who's bathroom this is, sees themselves as a prisoner, and so we do too.

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