If a plugin creates a custom post type with custom rewrite rules, but doesn’t update (flush) the rules, the end user has to revisit the permalinks page or the new CPT results in 404s; this is one reason for revisiting the permalinks page. Uninstalling that same plugin would, again, take a trip to the permalinks page to remove the rules.
Thanks John. I can appreciate the need in that scenario. Just didn’t think of it as part of the migration process.
@CodePotent you are right, I was also living in a lie like you said in Slack
It always calls the flush_rewrite_rules() inside the options-permalink.php
btw: That screenshot was taken with a VSCode extension called Polacode