Pretty sure it’s an issue with the merchant. In any case I suggest not spending that money as it could still come through as a delayed transaction (they ring-fenced only 1£ in the authorisation but will take the full amount during presentment, usually a few days later but could be up to 30 days in the case of hotels).
I also had a similar issue in the past where I booked a hotel room for myself on a debit card and a hotel room for a work colleague on a charge card and they reserved different amounts and released the authorization after different time periods.