the pronunciation of 辞書 is jisho, however, why does it sound like jishyo in prerecorded pronunciation online?
I'm unsure of the recording you are referring to, but just looking at jisho.org, the entry sounds like "jisho" to me. https://jisho.org/word/辞書 -- so it isn't a universal phenomenon!
One possible reason as to why your resource is saying "jisyo" is that one of the major systems of romanisation of Japanese (the Nihon-shiki system; see https://en.wikipedia.org/wiki/Nihon-shiki_romanization) uses 'syo' instead of 'sho' (as represented in the Hepburn system) to represent しょ. A computer-generated rendering of 'syo' might therefore just sound as such.