My wife & her sister had to travel to Gran Canaria at short notice as their brother was taken seriously ill.
They booked a Ryanair flight last minute from Shannon to Palma, not cheap but that's not the issue.
They both packed one piece of hand luggage ensuring to stay within the Ryanair guidelines. No problem on the outward journey.
A few days later, on the return flight, this time from Palma to Dublin, they were charged €40 each because their hand luggage did not fit into a measuring frame. This was despite the fact that both pieces of luggage were actually lighter than on the outbound journey as the didn't bother to bring back their toiletries etc. They were well within the Ryanair weight limits for hand luggage.
A number of other passengers had a similar experience. And worse still, they were bullied by the Ryanair staff who acted as if they were on some kind of bonus to penalise passengers.
In simple terms, another Ryanair rip off.