Ah, is this Ryanair's plan to divest from their all-Boeing fleet? :)

It should be pretty simple for Flightradar24 to exclude non-commercial aircraft from the data through, which would solve that problem.

There's also tons of data available in the ADS-B signal that should help distinguish between aircraft-motion-induced outages and actual jamming: https://mode-s.org/decode/content/ads-b/7-uncertainty.html

Unfortunately some of the data that's most directly applicable to determining aircraft attitude, like roll, is optional and rarely sent by aircraft, but yes I'm sure you could do a decent job of inferring maneuvering from change in heading and vertical rate (especially if you're looking at ADS-B data with high temporal resolution vs., say, every 10-60 seconds.)

From the FAQ, it sounds like they simply presume that anywhere with multiple low NIC values is indicative of interference.

> The GPS interference data is derived from NIC (navigation integrity category) values that we receive as part of the ADS-B protocol. We mark regions as affected if a significant number of flights in that area report lowered NIC values.

on a pure radar scan, what would return of formation flying like this look like to a radar operator? is it just one large dot, or can they distinguish the number of planes in the formation?