It’s working!
The solution was coded in the Dash code as follows:
# In order to work on shinyproxy
app.config.supress_callback_exceptions = True
app.config.update({
# as the proxy server will remove the prefix
'routes_pathname_prefix': ''
# the front-end will prefix this string to the requests
# that are made to the proxy server
, 'requests_pathname_prefix': ''
})
Thanks @fmichielssen again for your help