Man pages matching name xcb_xkb_set_debugging_flags in section 3:

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