Never had that issue on Vanadium browser, or Brave or even Firefox. I personally refuse to download an app if there is a website for the same. For a long time I was even using door dash in browser.

Why use a website at all, then? United has a reservations 800 number and you can print your boarding pass at the airport.

I get the sarcasm, but it's like comparing apples to oranges. Calling a number and talking to people is vastly different to clicking some buttons on your phone. App/website have almost same user interface, just different ways to get to that interface. Calling the number is totally different interface.

Often there is an extra fee to use the 800 number. (I'm not sure about United, but some places do that)