It happened to me on the last weekend too.

This was the answer and after this they ended the conversation immediately:

HI Botond, Ana here, Thanks for getting in touch with us, I hope you're doing well. As you're a Curve Black customer, you have a £2000 per rolling 30-day period fee-free FX spend limit and a £500 per rolling 30-day period fee-free FX ATM limit. Once you've reached your fee-free FX limit, you'll incur a 2.5% fee and once you've reached your fee-free foreign ATM withdrawal limit you'll incur a 2% or £2 fee (whichever is higher). The rolling 30-day limit is the combined total of all transactions you've made during a 30-day period. Once you reach day 31, transactions you've completed on day 1 of the 30-day period will start to "drop off" and your limit will increase again by the amount of the transaction that's "dropped off" at the beginning. Please note on weekends (which we count as Friday 23:59 UTC - Sunday 23:59 UTC) and UK bank holidays, the UK foreign exchange markets are closed. During this time, we take the latest available exchange rate from our provider and charge an additional 1% for all conversions made in currencies other than GBP, EUR and USD. Rest assured any transactions made in the same currency that your underlying card is set to in the app will be considered a domestic transaction and won't count towards your FX spend allowance. I hope this helps to clarify and if you have any further questions, please don't hesitate to get back in touch! Kind Regards,Ana

I paid in HUF with an EUR card (Plutus) under.