Originally Posted by
Ditto
I don't think you can reasonably expect to get both a refund for the upgrade and also downgrade compensation.
Given that you've flown in J for most of your journey, I suggest to just abandon the downgrade compensation request all together, at best you are looking at 75% of ~5% (miles flown in Y out of the entire journey) of whatever cheapest J fare exists for the route.
As for the delay itself - take a look at
https://www.lexology.com/library/det...5-c1a134c731ee which seems to suggests:
I suggest asking for 600€ and see how the airline reply.
I received a reply on July 2 after filing for compensation June 4. AF applied the 50% reduction so offered 300€. I replied with the references mentioned that even if the reroute arrives less than 4 hours later, because the departure moved more than 1 hour earlier, the reduction should not apply. Does AF actually respond to these replies disputing their calculations?