Have you ruled out a mycoplasma contamination? Other thing, maybe cells are too old because a high passage number of subculture. Try with thawing new cells and observe if this effect disappear.
SHSY5Y cells generally show two types of cells in culture adherent and suspension. May be suspension cells look like debris? or cells have old/high passage number. Check your media pH also.
I have tried various culture media. They did not grow well in the DMEM or MEM media, but they were well-maintained in RPMI1640 and DMEM-F12 media and growth.
I think reading an article Which will be sent to you, be useful.
@Syed husain Mustafa rizvi I have only the adherent Shsy5y, not the half suspension half adherent one.. media ph is most likely to be okay beacause other cell lines are growing fine with the media..