I am 100% sure that it is cached service. I am sorry, but I do not have a permission to publish the link to service.
I forgot to say that it seems like that when the map is accessed from Collector for ArcGIS on iPad. However, when I use AGOL on web I can see that tiles are coming.
The image is displayed with a 2-3 seconds delay when testing on Collector for ArcGIS. When using AGOL in browser the tiles are coming almost instantaneously.
However, I have tried just now to use the Collector APP on iPhone and it was much faster compared to iPad. I guess, that cache is used anyway. I was just wondering if there might be something special when setting cached layers to AGOL. I guess there isn't and the cache is used.
Thank you.