  In this article, we point out the issue of the first junction condition in
the Penrose diagram constructed by cutting and pasting analytically known
metrics with spherical symmetry by a static spacelike thin shell. We
demonstrate this issue by using two examples -- the generalized black-to-white
hole bounce with mass difference and the Schwarzschild-to-de Sitter transition.
The goal is to construct the corresponding Penrose diagrams without any
explicit or implicit illness at the thin shell. To accomplish this, we find
that two coordinate transformations are required unless a special condition is
met. The first transformation serves as the removal of the unwanted area while
the second one reconciles the two different coordinate systems on two sides of
the shell by removing an implicit discontinuity in the Penrose diagram of this
type. However, the second transformation brings a different kind of coordinate
singularity back to the event horizon. This coordinate singularity either
creates a degeneracy such that all four-vectors are in 45$\degree$, or a
degeneracy such that timelike vectors are parallel to the event horizon in the
resulting Penrose diagram. We give geometric explanations for the discontinuity
and this special type of coordinate singularity. We further show that no static
conformal coordinates can cover all of the event horizons without having
coordinate singularity at some of them. Lastly, we draw a comparison to the
Reissner-Nordstr{\"o}m solution.
