> Though I'm still surprised that some people run DB alteration on application start up

I think I've seen it more commonly in the Golang ecosystem, for some reason. Also not sure how common it is nowadays, but seen lots of deployments (contained in Ansible scripts, Makefiles, Bash scripts or whatever) where the migration+deploy is run directly in sequence automatically for each deploy, rather than as discrete steps.

Edit: Maybe it's more of an educational problem than something else, where learning resources either don't specify when to actually run migrations or straight up recommend people to run migrations on application startup (one example: https://articles.wesionary.team/integrating-migration-tool-i...)