  We study how the bounds on the abundance of Primordial Black Holes (PBHs) and
the constraints to the power spectrum (PS) are modified if a non-standard
evolution phase takes place between the end of inflation and the Standard Big
Bang (SBB). The constraints on PBH abundance and PS are computed using the new,
freely available, PBHBeta library, which accounts for the effects of
non-standard expansion and specific criteria for PBH formation. As working
examples, we consider three different scenarios: a pure matter-dominated (MD)
phase, a scalar field-dominated (SFD) universe, and a stiff fluid-dominated
(SD) scenario. While the background expansion is the same for the MD and SFD
scenarios, the PBH formation criteria lead to different constraints to the PS.
Additionally, the duration of the non-standard expansion phase alters the
bounds, with longer MD periods resulting in weaker constraints on the PS, and
longer SD scenarios leading to an enhanced abundance due to the dust-like
redshifting of PBHs. The modifications to the constraints are reported in all
cases, and we highlight those where the PS may be significantly more
constrained.
