Hi Michael,
Thanks for reaching out to us. I checked out the links you provided and, for me, I found that the Photo View showed the same thumbnail photos as the List View.
Here are screenshots of what I saw: Photo | List
As for the sources of those images, they’re coming from what looks to be a CDN on your website – a Content Delivery Network, which makes resources like images load faster on your site. These are your images, from your site, just moved to a bunch of different web servers instead of only being on one server.
This is coming from something that is not The Events Calendar. Do you have any caching plugins on your site? Any speed-related plugins? These could be the source.
If not, or you’re not sure, contact your web host to ask about this. The CDN being used seems to be MaxCDN – https://www.maxcdn.com/
I hope this helps!
Cheers,
George