Usage patterns
唐突に〈動詞〉to do something abruptly, without warning
He suddenly stood up without warning.
唐突な〈事〉an abrupt, out-of-context (question, remark, change, etc.)
I was surprised by the abrupt question.
話が唐突に〈動詞〉for the conversation/topic to change abruptly
I was confused because the topic changed so abruptly.
〈事〉が唐突に感じられるfor something to feel abrupt or out of place
That remark felt abrupt and out of place.