Bisq has rules in place to make the trading process as safe and convenient as possible for all parties involved, and it is important those rules are followed by users.
Penalties are a percentage of the trade amount, deducted from the offending peer's security deposit and offered as a compensation to the other peer during the dispute resolution process.
The actual penalty will be up to the values detailed below, depending on security deposit % and mediator's discretion, except for 100% penalties, that refer to serious violations and will always imply losing the whole amount (trade + deposit).
Alternatively, if good communication is established, peers can use trader chat to agree on a penalty amount to relay to their mediator.