Getting the correct road bike size, moving from MTB

Currently I have a Large Stumpjumper 2021 29er.

The size was advised by the shop I purchased it from. It was OK at first but I ended up having a bike fit to adjust a few things (slightly longer stem and get the saddle height/position dialed in) which helped a lot.

I am now looking at getting a Canyon CF 7.0.

The fitter is advising me to get a Large (based on measurements below),
however Canyon are advising to go with a medium.

My height is close to 180cm and 80cm inside seam.

Its not that I don’t agree the fitter might be correct, it’s just Canyon say the bike would be bike and I am not sure the best course of action or the differences I would feel going from the MTB to either sized road bike.
As its direct to consumer I am wary about purchasing a bike too large.

I’ve tried to look at the Geometry comparison on 99spokes.com / geometrygeeks.bike and while I can see the size differences I am not too sure what it would mean in real terms.

Fitter provided these measurements:

I do realize the main advice I’ll get here is

1. I should discuss further with the fitter (I 100% will, just not
   available at the moment)
2. Get a bike that I can test ride. (Wasn’t possible with Canyon and no local stock of similar bikes or alternatives to try)

But I wanted to ask here if anyone’s had any similar experiences with MTB to road or Larger bike than manufacturers suggested.
Or any general thoughts on it.