Is this a normal amount of EQ reduction for a vocal?

I don’t know anything about that genre, but those cuts don’t look excessive. The question that matters - does it sound right?

You could try a low shelf instead of 4 separate bells - you might get a smoother effect. I would also try a 12 or 18dB slope on the low cut and see if that sounds better. Steep filters at low frequency can cause phase / ringing issues.