Apparently, you will not see the Facebook data saver setting from the latest app update. Facebook is constantly updating their app and this feature has changed. It is now missing from the current media control settings. However, Data saver settings were still available in some devices which are not using the recent update.
To enable Facebook data saver from your Android Phone, Open the outdated app. Tap the Hamburger key or Settings. Then scroll down to Settings and Privacy, and Click Data Saver.
Why is Data Saver important? Enabling this option will reduce the use of data when playing videos at low quality or medium resolution. In Facebook app, playback video quality can also be set to Auto or Manual progressive resolutions such as 180p 240p 270p 360p 640p and 720p. If you don’t prefer to adjust the resolution manually, turning data saver on will help you out.
How do I limit Facebook data usage now? In the recent app update, you can still minimize the use of data. To do this, tap Watch tab then choose any video to play. Tap the video to see the gear icon or settings. From there you will find the Data Saver option. Tap it and enable data saver, otherwise tap optimized to get quality video resolution based on network conditions or bandwidth speed. Tap Quality to choose video resolution manually.
Moreover, it is also recommended to disable Autoplay Videos when scrolling from Newsfeed and Watch. To do this, Go to Hamburger key Settings> Settings > Profile Settings >Media and Contacts > Autoplay. Tap Never Autoplay Videos.
You may also be interested in blocking Facebook app usage from PLDT modem. This will allow you to set a time and day limit for social media access at home.