Hi, Visa is issued directly by Revolut, and as I know it is on tests now. Please check this thread on community - Email about Revolut Visa - #411 by kylo32
Sometimes there are problems with visa and Revolut is working on it.
Also I don’t know that Visa will replace MasterCard at all - more you can find there: European Banking Licence 🏦 - #57 by kylo32
On terms you can find information about Visa - https://www.revolut.com/pl/cardholder-terms?lang=en