This is a common misunderstanding.
One of the reasons for this, is that the Scrum Guide states:
The Development Team consists of professionals who do the work of delivering a potentially releasable Increment of “Done” product at the end of each Sprint. A “Done” increment is required at the Sprint Review.
At the end of a Sprint, the new Increment must be “Done,” which means it must be in useable condition and meet the Scrum Team’s definition of “Done”.
Development Teams deliver an Increment of product functionality every Sprint. This Increment is useable, so a Product Owner may choose to immediately release it.
This is often wrongfully translated into the idea that the only moment of releasing is at the end of the Sprint.
But, the intention behind these Scrum Guide statements is actually that at a minimum, each Sprint delivers a potentially releasable Done increment. In other words, each Sprint should have this at least at the end of each sprint.
Nowhere does it say that intermediate release or not allowed.
Since empiricism is the core concept of Scrum, try and think for yourself how empiricism can be fostered when it comes to releasing…
In Scrum, we strive for evidence, feedback, to happen as early and often as possible.
Releasing often is a perfect way of shortening the feedback loop with the end user.
The earlier you release, the earlier you can get feedback from your target audience, and the earlier you can Inspect and Adapt.
Thus, we should look for ways to release (parts of) the Increment early and often.
Continuous Integration & Continuous Delivery (CI/CD) is one of the techniques to enable this. DevOps goes hand in hand with this, and they both go hand in hand with Scrum.
For a Product Owner, even parts of the increment can hold Value for the user. As long as it is not released it is not generating feedback, but also not generating value. In other words, it creates waste! Since the Product Owner is the true Value Maximizer, it would be odd if the Product owner wants to wait until the end of the Sprint to release things.
So to summarize, the TRUE statement would be:
Releases are at least allowed aﬅer the increment has been approved in the Sprint Review