Hi @Ian Brooke
As a workaround, try pressing Esc when the suggestions appear to dismiss the popup without selecting anything.
If this happens in a browser-based program, test the same textbox in an InPrivate/Incognito window. If the suggestions disappear there, temporarily disable writing-assistance or language extensions, such as grammar, translation, or autocomplete tools, to identify which one is generating them.
If the popup occurs only in one particular program, it is likely controlled by that program rather than by a universal Windows setting. In that case, check the program for options named Smart Compose, inline suggestions, writing assistance, or autocomplete. If no such option exists, submitting feedback to the program’s developer would be the practical next step.
Thank you for your understanding