Man pages matching name al_put_blended_pixel in section 3alleg5:

al_put_blended_pixel.3alleg5.en	debian 10 / allegro5-doc
al_put_blended_pixel.3alleg5.en	debian 11 / allegro5-doc
al_put_blended_pixel.3alleg5.en	debian 12 / allegro5-doc