This campaign is not asking to take away IP from devs or publishers, they would still retain it.
Legally speaking, a game sold for a single payment and without clear stipulation of an end of service would be considered a Good under EU law. Tjis means you're purchasing a perpetual license to your specific copy of the game, but not to the IP or copyright.
Ross, the creator of the SKG campaign, goes into extreme detail on this very topic of goods vs services, and how the game industry is committing fraud by destroying a customer's ability to access the content their perpetual license allows.
I managed to put together a quick and dirty solarpunk flyer for the protest tomorrow! You can check it out here: https://slrpnk.net/post/24783048