Your conclusion is false, as you’re mixing stuff that shouldn’t be mixed here:

1. Spotify, Uber etc are popular because of their product, not the pure quality of their apps. People use Uber because they want to cheaply get somewhere, and Spotify cause that’s there all their shared playlists are.

2. People buy whatever tv is on sale when their old one breaks, but the vast majority will stay with their phone platform, so couldn’t care less what their apps look on the other platforms out there.

So, native experience does matter, but obviously only as one of multiple deciding factors.

> What does “bad iOS citizen” even mean?

Doesn’t look like native apps, doesn’t feel like native apps (come on, most multi platform frameworks don’t even get the scrolling right, one of the most basic forms of interaction), doesn’t use all of the platforms features to their fullest, as applicable for the type of app.

What I meant to say in my original message is that if you are using system default-ish iOS UI styling, Liquid Glass is not optional decoration. If you have your entirely own UI and design system, sure you don't need it. But many of these Flutter apps or other such toolkits are using it to approximate system default UI except either without the Liquid Glass parts or with uncanny and incomplete approximations of it.