When creating a new superflat world in 1.19.2, mineshaft structures are not generated. Using the /locate command gives coordinates but no mineshaft can be found at the coordinates or anywhere else in the world. This is true for Overworld and Desert presets.

Notes: Villages, desert temples, strongholds, and other structures all spawn perfectly fine, it's only mineshafts that aren't appearing. Mineshafts spawn as expected in the Tunneler's Dream preset.