Using Copilot for prose

[benthamite]

I have found it useful to enable copilot-mode in text modes, especially for composing email messages. The prose suggestions are sometimes very long, but one can just accept the first few words via copilot-accept-completion-by-word. (If you haven’t tried this, you may want to give it a go; I discovered it by accident.) However, although this works fine in e.g. org-mode and markdown-mode, it does not work in telega-chat-mode: copilot-mode is enabled but no completions are suggested. Any ideas on why this is the case and how to fix it?