The exception is Messenger, which does not work in a mobile browser at all. Attempting to use Messenger in a browser on mobile redirects to the App Store and tries to get you to install the app. As a result, the only time I even use Messenger is on my laptop.
Whenever I do use it, I am struck by the volume of spam I get from Facebook itself. I receive 5-10 messages a day from Facebook (far more than I do from actual people) nagging me to boost posts on various pages I manage, or all the traffic I am missing out on by not giving Facebook money to inject ads for my pages into peoples’ News Feeds, messages like this one:
Page admins boosted posts similar to yours and reached more people.
Try boosting this post to reach more people.
What I find particularly galling about this constant hectoring by Facebook is that the only evidence in support of how well boosted or promoted posts are performing come from Facebook itself. On any other website, I would be able to run my own reporting and analytics to understand how well various posts are performing. Facebook is a closed system, though, so I have no option other than to trust them.
This setup makes me deeply skeptical of their entire advertising ecosystem.