I like your app's simple and beautiful design. Some suggestions:
Your "install app" page says Safari even though I'm using Firefox on the desktop. Perhaps you can change the instructions based on browser detection
Images are always displayed in full height. Will you consider setting a maximum height for images so tall images won't affect browsing the posts?
The login page says "Due to CORS, all requests to will be proxied through wefwef.app". Can you elaborate and give reassurance that privacy would be respected by your app? Perhaps a privacy policy under the settings page would help.
The profile page has a very short list of instances. Is there a logic on how those instances are selected? I support that you are selective about what instances are included. I hope to see the instance managed by weirdos to be excluded.