[whatshisface]

If by "this effect" you mean particles fluctuating so that every field has at least some role to play in every interaction, it also applies to empty space, which has a nonzero energy density due to its own fluctuations. In fact, empty space has an enormous energy density due to this stuff. It is so enormous that it's implausible, and that's considered to be one of the major unsolved problems in physics.

If by "this effect" you mean radiation occasionally interacting to produce particles, that actually doesn't change the amount of gravity in the universe when it happens, because energy is what gravitates and it's conserved in particle interactions.

https://en.wikipedia.org/wiki/Cosmological_constant_problem