Dropped text-input events when receiving application hangs for a moment
(this might be a compositor, toolkit or even protocol issue, but filling it here as a starting point for investigation)
When a text-input-using application hangs for a moment, further key strokes made in squeekboard are dropped instead of being buffered and delivered/handled once the app gets back to its event loop (unlike virtual-keyboard keystrokes, which are all eventually processed correctly).
The most visible examples of that are phosh search bar when it's filled with plenty of applications, or browser address bar when it's busy rendering a heavy page.
So far I've seen it only with gtk apps, but haven't really looked very hard to confirm whether it happens with other toolkits too or not. A gtk app with text entry that reacts to incoming text with sleeping for a second should be a good reproducer.