Is it possible to lose delegated funds?

Yes, therefore it is very important to delegate coins only to the most professional validators and diversify delegation. Validators cannot in any way take control of the coins of the delegators, but the network provides penalties for disruption of performance. If the validator skips 12 blocks in a row, then 1% from the stake of the masternode will be cut (burned), and the masternode will be excluded (deemed inactive) from the validation process until the new transaction is sent for being added to the list of active validators. If an attempt is made to double sign the same block (the data in the blocks will be different), then 5% will be cut (burned) from the masternode’s general stake and the forced unbond (partition) of all delegated funds to the masternode will take place. More details about risks and tasks for delegators can be found in the documentation https://docs.minter.network/#section/Delegator-FAQ