Can we talk about this cut into the frame support below the window and, now, the unsupported downward newly displaced force it is creating?
As much as we like to shit on them, this shouldn't be a problem
The framing each side of windows is the load bearing element, nowadays new builds in some places just fix windows with expanding foam
Also looking at the amount of timber in the section we can see of the original, this thing is way over built. It also looks like the internal walls are clad in board rather than sheetrock, so yeah, not a problem as far as fucking with structural elements goes
I mean, I'd have made the opening larger, framed out the opening and then put the vent in, which if you can, is the proper way for all sorts of reasons
But as long as they weather-seal this properly, what they're doing is no issue
What I can't get over is the almost belligerent foolishness of not covering the work surfaces
They've got enough fucking cardboard ffs
5 minutes at the start with a craft knife and some duct tape when they were fresh, and they'd have saved themselves an hr at the other end when they were tired and wanting to finish and have a smoke