Here's the official news: https://www.efteling.com/nl/blog/nieuws/20220124-nieuw-hotel-en-vernieuwd-themagebied-in-2024
So we'll get a new attraction opening in 2024, with a throughput of 1250pph, as well as some sort of 'theme world', which makes me think this investment might see more than just the attraction. No news on what the attraction is yet, and I'm still a little hesitant to refer to it as a ride just yet. The park will spend 25 million euros on this new investment (for comparison, Symbolica was 35 million)
The park will also open a new hotel in 2024, next to the main entrance, so that it will overlook Aquanura (the water show) and the Fairytale Forest. It will have 7 floors, 143 rooms, 2 restaurants and a spa, and represents a 50 million euro investment. For comparison, the most recent hotel offering (Loonsche Land) cost 30 million euros, and the previous (Bosrijk village) cost 52 million euros, but both of those have pretty substantial outdoor bits too, which seems less like with this hotel.