This sounds like a bug since the app should never infinitely load. I am unable to reproduce this issue however when I tested against a test server. When I brought the server down the client immediately shows an error.

It sounds like the server you are connecting to isn't offline but might be ignoring requests. When this happens the network call can take a few minutes to complete since the app has some retry logic in place. There isn't really much I can do here since it's impossible to tell between the server ignoring requests due to maintenance and the server being busy due to high traffic. Ultimately it will be up to the server owners/Lemmy server code to return a specific error for this.