So I take this is a security concern. How do you feel about the fact that when you open a webapp in your browser, you re-download that app code every time? That the server can send you a backdoor every single time, made just for you, and nobody else will ever know? And that you can't check the "hash" of the webapp, like you can with an app?
On the other hand, an app is sandboxed, too (on mobile OSes like Android and iOS). When you download it, you can check a hash that you can (if you want to) compare with a friend to see if they got the same app. With an app, there is intermediary (the "app store") that would need to collude with the developers to send a backdoor just for you, and even then you would still have the app binary as proof.
That's always a question I have with "secure" web services: if you use ProtonMail, you trust that Proton doesn't send you a web page that leaks your key. But if you trust Proton for that, what's the point of the end-to-end encryption? When you use the Signal app, the whole idea is that you don't have to trust Signal for the end-to-end encryption, at all.