Are you on the prepaid card, Artur? 
If you’ve recently started using your Monzo card then you might find that you’ve hit your daily withdrawal limit; this can be increased with verification. @Naji made a post about limits earlier this year 
New Limits! (here’s a table directly within the terms page: https://monzo.com/terms/#charges)
Your best bet is to give the team a shout via the in-app chat 
They might be able to sort something out for you 