Ok so Mastercard have sort of fixed their foreign transaction calculator now for the VES/GBP pair but they need to use scientific notation to do it.
This works out to be 1 VES = 0.0000002 GBP
From this I could work out that Monzo is just using the Mastercard rate.
So my issue is with Mastercard, not with Monzo.
This currency pair has remained the same ever since 14th May 2021 yet during that time the VES has devalued more than 100%.
I think what Mastercard does is change the rate in “blocks” spanning several months so early after the change things are really cheap but as the weeks pass by due to hyperinflation factors things gradually become more and more expensive.
Don’t have the same problem with Visa. In fact the Visa rate as of today is about 12% better than the Mastercard one.