A redditor said that Scrum is not agile:

I agreed, somewhat#

I have a problem with Scrum. While it’s a solid framework when applied correctly, Scrum as a product is flawed. It’s not user-friendly. People need extensive training to use it properly, and mastering it takes years.

Another issue is its generic nature. Scrum is intentionally incomplete, which creates problems. Development teams often forget that adopting Scrum also requires integrating other practices, such as those from Extreme Programming. You can’t effectively use Scrum without technical excellence or practices like for example Test-Driven Development.

Scrum was created more than 20 years ago, when products were simpler and the challenges were different. Today, the biggest hurdle is scaling, yet Scrum completely ignores that.

Finally, the certification industry around Scrum should just disappear. It doesn’t work. It just creates the illusion that someone who takes a short course and earns a PDF certificate is qualified to do the scrum master job.