There are a lot of image/gif(?) posts that I haven’t been able to view either on the Memmy (Apple) app or in-browser with either Safari (Apple) or Google Chrome. I imagine it comes down to the file types as well as the lack of native hosting to standardize posts of different media types, but I’m not the techiest person to consult on that. One downside of the fediverse is the lack of standards for file hosting/conversion/displaying to ensure that all media can be accessed regardless of the browser/app (or, alternatively, the lack of an all-encompassing app for all devices [Jerboa sounds like the closest to this to me but it is not available for iOS yet]), as well as the self-funded nature of the instances commonly not having the budget to natively host multimedia content such as videos.