Hi Kolmodor,
I also noticed 40 MHz channels are not working on my build based on a snapshot some weeks ago. Rural area, so uncongested 2.4 GHz environment, also setting noscan option didn't change anything. What made me even more suspicious: I've got an D-Link DAP-X1860, which is almost the same device, featuring the same chipset - I'm running v22.03.05 on one unit (and a v22.03-ish snapshot build on another one) and 40 MHz channels work perfectly.
After digging around in the forum a bit, I found the following thread: MT7621: WDS with channel width > 20 MHz and AX not working in newer snapshots - #24 by ThiloteE
So, yeah - it's a bug, but according to the topic, it should be fixed by now. However, I didn't have time to try out a more recent build.