I spend abroad quite regularly, so it was quite annoying when I spent money on my card, was told the cost of the transaction and seen it clearly in my spending list, then 2 days later the transaction cost was completely different, without notification or reasoning.
I understand the whole process of foreign transactions being processed with delays, see this post for more info: Foreign Transaction
But in my opinion Starling doesn’t do a good enough job to make it clear when a charge is pending and when it is confirmed in your spending list. A simple tag or marker would suffice. Most of the existing legacy banks do this already (via pending transactions).