just asking … 
… but on the wrong forum 
Assuming you want to see it on the default style (and not the the humanitarian, cycles or public transport maps, nor on OsmAnd or any of the Garmin renderings), go to https://github.com/gravitystorm/openstreetmap-carto and file a bug report/enhancement request.
BTW, you do you tag nightshops ? AFAIK, there is no dedicated tag for this kind of shops on https://wiki.openstreetmap.org/wiki/Key:shop. I though you had to map them as a shop=convenience with opening hours during the evening/night. If that is the case, your chances to get a special icon are slim.
Please note that e.g. OsmAnd shows which shops are open at this moment.