This is Cash App trying to force users to use the app if they have it installed. You have to go out of your way to copy the QR and then open your preferred wallet. It’s smart UX but meh 😑
Discussion
How does CashApp get preference like that?!?
The whims of iOS 😨
Looks like it has to do with URL schemes.
https://developer.apple.com/documentation/xcode/defining-a-custom-url-scheme-for-your-app
So https://cash.app seems fitting to want to open in CashApp. There's probably a way to give the user an option using a custom url scheme and prompting the user.
I wonder if btc/lightning app have a url scheme already....