IME Wildcard redirect URLs have become more common in recent years due to the rise of preview environments. If you're deploying a git branch to Vercel, and you now want to log in to <project-name>-git-<branch-name>-<scope-slug>.vercel.app, then you don't want to bother with configuring a different redirect URL for every branch name. Enter the wildcard.

Ideally wildcards are only used in dev/staging environments, but if the system allows for misconfiguration, the system will be misconfigured.