I’ve now seen this to many times for it not to be dark design. In iOS when going from a link in YouTube or the Hangouts app the first time you attempt to follow link you are presented with 2 options (image 1) however link two doesn’t open Safari as it suggests but takes you to the App Store to install The Google App (if you don’t have it installed). If you quit this action and dismiss the sheet and click the link again you will this time be presented with the correct 3 options (image 2) of which the third option is now open in Safari and works as expected.
Can anyone else confirm this on there devices? Open a google owned app and try to follow a link and see what options are presented.