When using the "back" button on my phone, Facebook has started interrupting the process with a pop-up menu asking what app it should use to "Open with." And they seem random: emergency call, settings, Google assistant, etc.
I would try clearing Data, cache and force stop Facebook app maybe a glitch .Samsung Galaxy S7.
If you long press the Facebook app >tap info>go to storage and clear in that order I described earlierI can't find a way to clear data or clear cache except to optimize/clean it through settings. Force stop did nothing.
Any time you have a problem with a Facebook app, it's almost always Facebook's fault. (They promote "developers" whose resumes I'd throw in the garbage at first glance. Mark Zuckerberg is [or was?] a good developer, but the people they hire? Not so much. [But then, I've only been doing this for 46 years, so what do I know?])Only in the Facebook app, as far as I have seen.