My first time shooting a film stock with an insane iso like this, previously I hadn't gone for anything higher than iso 400 and mostly colour. I also pushed myself a bit out of my comfort zone with the 28mm, as I rarely feel comfortable shooting below 50mm.
Somehow this was the only shot of the roll that seemed properly exposed, with many others mildly or wildly underexposed. I've since checked the lightmeter of my XG9 against other references at 3200 iso (or rather 1600 iso -1 stop because the XG9 doesn't support 3200 iso). But unless I push it way harder than I'd ever do irl, I see no fault there. Edge markings and this shot are also fine, and the camera has previously behaved normally, so it was probably just a skill issue somehow.
A little update on this. I went back to the lab and they apparently developed it at the development times for 800 iso, because that was what the table of their developer listed as the normal for Ilford Delta 3200. In fact, it didn't even list dev times for 3200, only 400, 800, and 1600.
This also checks out with this shot, because I vaguely remember messing up the math in my head, thinking that I went up and down a stop to cancel out, while I actually added 2 stops of exposure. Something I realized when cycling away. So ironically this is the only good shot precisely because it's 2 stops overexposed when measuring the church wall, which counters the 2 stops of underexposure from development. This shot would've been completely nuked if it had been developed as I intended.
Anyway, some learning for me and the lab. Next time I'll tell them the intended iso with b/w rolls.
Ask them if they have push developers. It's likely to be a vitamin C based one, which is recommended for T-grain films like this. Typical ones would be XTOL, DD-X, Microphen, T-Max, Acufine.
Note the developer they use and check the recommended ISO setting for Delta with that, so you can properly expose the film.
When dropping off the film, write down the developer you want them to use and the ISO setting you shot at.