The this app app has multiple bugs and issues throughout. If all you want to do is look at art, DeviantArt is totally fine. Whenever you want to get just a *teensy* bit more advanced, though... First of all, the sharing feature is broken. You can copy the link of some art, but from what I’ve tried that’s basically all that works. The share sheet freezes the moment you try to summon it, and you can’t download artwork either. It says you can, but actually pressing the button will do nothing. I *did* give it access to my photos and videos; it still doesn’t do anything. Maybe it’s an app-exclusive download, and you use the share sheet to save something to your photos, but unfortunately in that case the share sheet is still broken. Also, when uploading art, you cannot change the display size, meaning it’ll most likely be stuck at a ridiculously low resolution until you hop on a computer, or even the web version of mobile DA, and fix it. Speaking of the web version, isn’t it funny how that version is way more functional than DeviantArt ?
TL:DR if you only want to view others’ art, and that’s WITHOUT being able to save them to your phone, DeviantArt works. For the people actually uploading art... it’s frustrating, to say the least.