Overview
There are multiple Actions deployed in the Post-Login trigger, and some of them read the Actions cache to get some values. This article explains whether it is a guaranteed to get the same value in the other Actions of the same flow.
Solution
Yes, the same cache value is guaranteed to be available to all actions in the same flow, assuming the cache has not expired. In other words, the cache is consistent across a single execution.
However, there is one exception: if the user is temporarily redirected from the flow (for example, due to an Actions redirect, custom MFA logic, etc), there is no guarantee that the same cache item will be available to the Actions after they resume from that redirect later.