Thanks, reddit team, for fixing this. Both the new OPEN button anchored to the top, and the new bottom sheet work as desired now.

My comment above was about a previous version of the "open in app" bottom sheet from a previous version of the mobile website.

Both mobile safari on iOS.

This works fine in android. You can associate your favorite app with the reddit links. There is surprising depth in the settings regarding this feature.

I had this issue for the longest time and was very frustrated. I learned you can hold the link and then click "Open in Reddit" in Safari to get around this.