I guess it's a bug, not a feature. Happened to me twice in a row now:
1. I'm playing a rapid Arena on my phone, android app.
2. I search for next game in Arena. Due to my rating, it takes a while to find an opponent.
3. I switch to another app on my phone, e.g. messenger message popping up.
4. I go back to chess.com app. Instead of seeing a new game started or my search cancelled, the app is now frozen, I cannot cancel the search or start a new game.
5. I have to force-close the app. In the meantime, I see in my archive that a game was started for me, it was abandoned in 1 move, and I lost rating points.
Tl;dr - switching to another mobile app while searching for an Arena game causes an abandon loss.