> For me a particularly frustrating aspect is the way the UI moves around a lot. I’m quite anxious to click anything until all the loading spinners have stopped in case I click the wrong thing. Then I could be taken to a page or feature I’ve never seen before.

This is a common antipattern that doesn't get talked about enough. It's very common in the era of interactive ads, websites with 3rd party web UIs layered on top, lazy loading, and just "rich" UIs in general. A user needs to be able to trust what they are about to click. This is fundamental.