Because some of keet remains closed its not fully certain what the issues are, which is probably the biggest issue, but from having used it here is some ideas and speculationsI have

Direct IP connections exposing your IP. These do not happen all the time tho

Main id, username and screen name exposed to every room

Seems like no forward secrecy on the P2P distributed room data

Seems the room data can be freely distributed to anyone that knows it exists but there is obviously an issue identifying it given peers also encrypt connections to each other

Notifications on mobile in some part (said to be encrypted obviously) go via Google and apples servers

Each room message is identifiable to each device

Screenshot message data might be matchable to room hash data

Might be possible to forge results with their username system then maybe mitm is possible etc