A few other resources because this one seems to read just like a PR:
https://arstechnica.com/cars/2022/11/rolls-royce-tests-hydro...
https://www.reuters.com/business/aerospace-defense/rolls-roy...
https://www.bbc.com/news/business-63758937
https://simpleflying.com/rolls-royce-hydrogen-tests-turbine-...