I’ve had it happen in the Starbucks flavoured non-dairy creamer as well. It seems to happen either when it’s been sitting a while, or if it gets shocked by hot liquid rather than a slow gradual pour (“milk” first).

I don’t recall having had it happen with Earth’s Own Barista Oat, which is what my local (Canadian) Starbucks all use, but it’s been a hot minute since I’ve had any.