From their website:
Fed4FIRE+ is a project under the European Union’s Programme Horizon 2020, offering the largest federation worldwide of Next Generation Internet (NGI) testbeds, which provide open, accessible and reliable facilities supporting a wide variety of different research and innovation communities and initiatives in Europe, including the 5G PPP projects and initiatives.
They have an Open Call for Proposals closing on 15/03/2022, but the initial proposal deadline is 16/02/2022 @ 1700 EST.
More details here: