When I’m travelling, often a hotel or car rental company will want your card as a security deposit so they can put a ‘hold’ payment on it.
For example, Avis have a fuel deposit of about £50 - they put it on your card as a pending payment and when you deliver the vehicle back with fuel in it, they cancel the pending payment and don’t really charge you for it.
If you use a credit card in this scenario, you don’t have any issues because you won’t pay the balance for a month. However, when you use Monzo any payments like this are deducted from the balance immediately. This means that it’s still better to carry a credit card for these kind of security deposits.
Would be great if Monzo could find some way to solve this problem.