Man pages matching name xcb_xfixes_region_extents in section 3:

xcb_xfixes_region_extents.3.en	debian 10 / libxcb-doc
xcb_xfixes_region_extents.3.en	debian 11 / libxcb-doc
xcb_xfixes_region_extents.3.en	debian 12 / libxcb-doc