Extbase clears the TYPO3 cache automatically for update processes. This is called Automatic cache clearing. This functionality is activated by default. If a domain object is inserted, changed, or deleted, then the cache of the corresponding page in which the object is located is cleared. Additionally the setting of TSConfig TCEMAIN.clearCacheCmd is evaluated for this page.
The frontend plugin is on the page Blog with uid=11. As a storage folder for all the Blogs and Posts the SysFolder BLOGS is configured. If an entry is changed, the cache of the SysFolder BLOGS is emptied and also the TSConfig configuration TCEMAIN.clearCacheCmd for the SysFolder is evaluated. This contains a comma-separated list of Page IDs, for which the cache should be emptied. In this case, when updating a record in the SysFolder BLOGS (e.g., Blogs, Posts, Comments), the cache of the page Blog, with uid=11, is cleared automatically, so the changes are immediately visible.
Even if the user enters incorrect data in a form (and this form will be displayed again), the cache of the current page is deleted to force a new representation of the form.
The automatic cache clearing is enabled by default, you can use the TypoScript configuration persistence.enableAutomaticCacheClearing to disable it.