Unable to access dynamic created Graph id in callback

I have a large dashboard with many charts and tables. hence cannot post code here
Dashboards with Graphs, Tables are created dynamically.
Once dashboard has rendered, i do see one of graph with id=“synth0”,

I have callback as below
Output(“download-image”, “data”),
Input(“btn_image”, “n_clicks”),
def download(n_clicks, fig):
print(“Print fig”)

but i dont get this graph in callback
Print outputs as None

Any help/ideas to access this graph?