I’ve had good experience with actual Scrum, as described by The Scrum Guide (https://scrumguides.org/scrum-guide.html).

I have had terrible experiences with bastard scrum: Standups as manager reports, sprints as death marches, stories without a definition of ready or done, stories added during the sprint, no backlog refinement, etc.

In my experience many companies doing “scrum” are actually doing daily manager reports and weekly top-down deadlines of fixed scope, while calling these “standup” and “sprints”.

In my 15-year career I’ve only worked with one company doing real Scrum, and all the companies doing bastard scrum were startups.