This is probably better phrased as "LLMs may not provide consistent answers due to changing data and built-in randomness."
Barring rare(?) GPU race conditions, LLMs produce the same output given the same inputs.
Are these LLMs in the room with us?
Not a single LLM available as a SaaS is deterministic.
As for other models: I've only run ollama locally, and it, too, provided different answers for the same question five minutes apart
Edit/update: not a single LLM available as a SaaS's output is deterministic, especially when used from a UI. Pointing out that you could probably run a tightly controlled model in a tightly controlled environment to achieve deterministic output is very extremely irrelevant when describing output of grok in situations when the user has no control over it