It used to be the case that saying you'd applied for one was enough - not any longer.

Although a pinch of salt is often needed on Reddit:

"We applied for our ETA yesterday morning and have heard nothing yet. We missed our flight last night from Toronto, and when we got to the airport there were easily 70+ people stranded because of this ETA outage."

https://www.reddit.com/r/ukvisa/comm..._common_issue/