Water droplet sound, no notification

My iPhone is up to date to the latest software update, iOS 17.4.1 .

My phone sometimes makes a random water droplet sound, as loud as a notification, but when I check the notification center there’s no notification of any app. I have never heard this sound before, and I have not recently downloaded any new apps. I also have notifications off for most of the apps I have installed. The noise sometimes appears when the phone is asleep and also when I use it. I checked if it may be the weather app indicating it will rain soon (sounds logical, maybe new update I didn’t know about) but the forecast is clear.

What could it be?