Whenever I type the word voiceover, XD automatically changes the caps so it appears as VoiceOver. How do I turn this off? (I'm on macOS Big Sur 11.6.)
I wasn't able to replicate the issue. Is it possible you turned title case on for that text object? Do other words get capitalized as well? Also, you can try turning spellcheck off, from the Edit menu.
I don't think there's autocorrect in Xd even with spellcheck on, could it be some feature of the system, plugin or another program?