The circulation of counterfeit banknotes in society is not exactly a novelty. Almost all security substitutes, there are those who can perfectly replicate the current notes.

According to the Bank of Portugal, in 2021, 10,836 counterfeit euro banknotes were withdrawn from circulation in Portugal.

A counterfeit bill is not refunded...
According to the Bank of Portugal of counterfeits seized in circulation, growth of 10% in 2020. The amount of contractions detected is residual in relation to the total number of banknotes in circulation.
The denomination of 20 euros continues to be the most seized.  The €200 denomination, despite being one of the most important banknotes, is the one with the fewest counterfeits detected (in 2021, "only" 71).

The seized contractions can be easily identified in 2 identified elements, without resources like instruments, just playing, observing and tilting a note to identify the relevant resources (method “Touch – Observe – Tilt").
Banco Portugal warns that it is important that users always receive receipts. A counterfeit banknote is not refunded, which implies a loss for the person who accepts it..
Banco de Portugal and the European Central Bank publish information on the characteristics and security features of euro banknotes on their respective websites.  Banco de Portugal also provides training for different audiences on this topic.
As the most secure banknotes, they integrate highly secure security features, which make the currency unique in one of the world's.