  On a bounded three-dimensional smooth domain, we consider the generalized
oscillon equation with Dirichlet boundary conditions, with time-dependent
damping and time-dependent squared speed of propagation. Under structural
assumptions on the damping and the speed of propagation, which include the
relevant physical case of reheating phase of inflation, we establish the
existence of a pullback global attractor of optimal regularity, and
finite-dimensionality of the kernel sections.
