So this is a bug with UserInputService.TextBoxFocusReleased not firing when when the TextBox is Destroyed inside the focus lost event. This code can reproduce it.
wait(4)
script.Parent:CaptureFocus()
script.Parent.FocusLost:connect(function()
script.Parent:Destroy()
end)
We have some changes to textboxs that will be coming out early next year that should fix this.
If this impacts your game a lot, I have a hacky solution that you can add to ChatBar:ResetCustomState()
self.TextBox:CaptureFocus()
self.TextBox:ReleaseFocus()
Add this just before self.CustomState:Destroy()