This bug appears to be independent from the device. I have the same issues with iPhone SE, iOS 14.3, many others in our community have reported this, but exclusively related to fairchat app.
Seems to appear especially in threads or conversations, and/or in private channels, like this: certain messages are not loaded when trying to open them, instead Fairchat app freezes and needs to be closed & reopened.
Reopening does not solve it, the same behaviour remains.
The number of affected messages is rising since the problem appeared, also with different (wechange) servers. As I am rarely using the fairchat chamnels I cannot say if the issue is server related. The concerned messages are displayed with the native RC mobile and desktop app without any trouble, however.