Long cardholder surname - how does it work?

Revolut doesn’t ask for a preferred way of putting a cardholder name on the card.
What’s the standard practice for long names? (official limit of MasterCard is 22 characters)
Shortening the middle name by default? Or shortening the first name?

Could anybody with a middle name (or 2-part, long surname) give here some details?

I have a name with 16 i dont know if they shortening
But i didnt write my middle name and it appears now as name lastname