There’s the initial amount but the exchange can change over the time it takes from you paying and their bank collecting the money. If you look at the transactions in detail it should show the final settled exchange rate
It does (£1 = €1.10), but if that’s the case it would make more sense for the initial transaction to tally (i.e. the debit(s) actually match the balance at the end of that day) - and then subsequently adjust if there are changes.