I would probably lose the large wood frame and either have a mirror glued directly to the wall or use a minimalist frame as thin as possible in black.

With a low bulkhead over the sink wall, I would stop treating the mirror as a decorative object and treat it as a fit problem first. In a room like this, a large wood frame usually adds exactly the thickness and visual weight that make the area feel more awkward. A simpler mirror, or even a clean wall-to-wall glass mirror with a minimal edge, is usually the safer move.

If possible, I would line the mirror width up with the usable vanity zone below and keep the top edge intentionally below the bulkhead instead of trying to fight it. Then let the light fixture do more of the visual work. A slim black or metal fixture that projects less can help the whole wall read cleaner than a heavy framed mirror trying to fill the space.

I work with a lighting and metal hardware manufacturer, so I look at this from a production and QC perspective. The details that matter here are mirror thickness, frame depth, how far the fixture projects, and whether the reflection height still works comfortably for the tallest user. A taped mockup on the wall is worth doing before ordering anything custom.

If you have floor space in the room, could you build out the soffit to the floor and then move the vanity and mirror forward to your new full height wall?

I like the minimal frame approach, I’d also mount a height adjustable mirror to the side for more flexibility

*showing this one for concept, not sure this is high quality

the W/D is out into the room, Build out the wall and reinstall the vanity so it works for everyone... I'd personally build out the whole wall with a solid surface countertop and an undermount sink so you can use it as a laundry folding counter and a hand wash clothing laundry sink as well. add storage above as needed, shelves or closed cabinets.