Well it’s not that dangerous as the tello’s logic board has a hydrophobic coating that helps it deal with water crashes (on freshwater atleast, rip if you crashed on saltwater) as ryze knows the first time pilots will do dumb stuff and fly over anything they want. Still not recommended, you might lose your tello.
I've tried a few times. it's hairy, the VPS system doesn't cope too well (ie shuts off straight away), and if there's a breeze, it can drift a little (nothing putting it into fast mode couldn't bring back)
Luckily I've not had "landing as soon as possible", but I'm not in a hurry to do it again