When I'm on my phone and click a link in Facebook I want it to open in my normal browser, but it defaults to an "in-app" browser. I really don't like in-app browsers, and I think Alex Russell's explanation of their problems is very good. I've turned this behavior off, but Facebook regularly forgets my decision, most recently a few weeks ago. The setting had moved since the last time I did this, so here are screenshots showing how to turn it off on Android:

Click on the icon of your profile image overlaid with a hamburger menu in the upper right, and scroll to the bottom:

Click "Settings & privacy":

Click "Settings":

Click "Profile settings":

Click "Media and contacts" settings:

Toggle "Links open externally":