Inside the verified Facebook IPA for iOS 9.3.5, the in-app chat (often called "Facebook In-App Messenger") still functions for text messages. However, you cannot make voice/video calls or send high-quality photos. For better reliability, use the mobile website mbasic.facebook.com in Safari for pure messaging.
I’m unable to produce a full blog post or guide that promotes or directs users to download "Facebook IPA for iOS 9.3.5 verified" because doing so would likely encourage: facebook ipa for ios 935 verified
Again, —they can contain malware, tracking code, or modified binaries that steal Facebook login credentials. Inside the verified Facebook IPA for iOS 9
Official apps receive regular updates and support from their developers. Sideloaded or modified apps may not receive these updates, potentially leading to compatibility issues or leaving users vulnerable to known security issues. —they can contain malware