  Over the last few years, low- and high-redshift observations set off tensions
in the measurement of the present-day expansion rate $H_0$ and in the
determination of the amplitude of the matter clustering in the late Universe
(parameterized by $S_8$). It was recently noted that both these tensions can be
resolved if the cosmological constant parametrizing the dark energy content
switches its sign at a critical redshift $z_c \sim 2$. However, the anti-de
Sitter (AdS) swampland conjecture suggests that the postulated switch in sign
of the cosmological constant at zero temperature seems unlikely because the AdS
vacua are an infinite distance appart from de Sitter (dS) vacua in moduli
space. We provide an explanation for the required AdS $\to$ dS crossover
transition in the vacuum energy using the Casimir forces of fields inhabiting
the bulk. We then use entropy arguments to claim that any AdS $\to$ dS
transition between metastable vacua must be accompanied by a reduction of the
species scale where gravity becomes strong. We provide a few examples
supporting this AdS $\to$ dS uplift conjecture.
