Originally Posted by
econ
I was just about to mention the same thing. It's not just an Airbus issue, I've noticed the same on the 7M8/7M9, so probably on the new F seat in general. I can barely fit my one of my bags underneath (and some might argue that it doesn't completely fit). Had no problem fitting it under the older domestic F seats, or any Y seat I've been in for that matter.
I might start taking a tape measure with me -- I wonder if the 7M8/7M9 are slightly higher off the seat track or has slightly less crud hanging off the bottom of the seat because those are the ones I mentioned where I can "barely" get my bag under those with a bit of persuasion -- at least far enough to make the FAs happy (though IIRC without the annoying seat divider thing so possibly an older version of the new seat) -- for the 321 after three flights and trying various orientations (e.g. the 7M8 it has to go under "top" first because the bottom flares just enough to make it not a thing) and "gentle squishing") I've had to just punt to the overhead.
321 in Y (21F, at least) fits very comfortably