Good stuff, though from my understanding a slot is a airport allocation to land/take off. So an airline would have slots at the departure and destination airports and with that, some would be forced to make the flights to cater for the other end connection.

So I had a dig and see if the EU did anything and they did it seems - https://www.consilium.europa.eu/en/press/press-releases/2021...

Though it does seem that the results are mixed and good coverage here: https://www.airportwatch.org.uk/2022/01/european-airlines-ha...