I thought Cuban cigars were readily available in the EU?...............
Correct—Cuban cigars are legal in the EU.
However the island has had a brutal last few years—a perfect storm of Covid, hurricanes, government and economic collapse.
The result is cigar production is probably less than half of what it was pre Covid.
In some countries (like Spain) the government sets the prices for Cuban cigars while at the same time there is a quota (set by Cuban suppliers) for the country. As a result the Spanish inventory sells out quickly and is very difficult to maintain.
The solution—a black market that grabs inventory where it can around the world and provides it to where there is strong unmet demand (like Spain).