Misuse-of-facility markers are added when a bank believes an account holder has used the account outside the terms — typically an unpaid overdraft or a returned direct debit chain.
First-party fraud markers require evidence that you knowingly acted with intent to defraud. The evidential bar is much higher, and it must be evidence that would be admissible in court.
In practice, banks often mis-label misuse cases as first-party fraud. This is where challenges succeed — the bank cannot meet the higher evidential standard on review.
If your marker is labelled first-party fraud, always ask the bank to produce the evidence. In many cases they cannot, and the marker must be downgraded or removed.